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No. & Date Asked	Question
# 864 :: 4/15	1. Suppose a 95% confidence interval for the mean daily sales for a sample of 100 days from an internet site is:($236, $318). a. Will a 99% confidenc. . .
# 863 :: 4/12	Describe how measurements and regression analysis are interpretations of reality and not reality itself. (One page answer). . .
# 862 :: 4/12	A recent survey of community colleges found the average age of attending students to be 29. A class of 24 students has a mean age of 26 and a standard. . .
# 861 :: 4/8	Lab 6, confidence intervals, two sample and paired In class we discussed GM testing a brake light. Suppose that this is very expensive, time-consum. . .
# 860 :: 3/30	Problem # 1: Clothing for Runners: Your company sells exercise clothing and equipment on the internet. To design the clothing, you collect a data on. . . Confidence Intervals, Margin of Error
# 859 :: 3/18	1) Spinifex pigeons are one of the few bird species that inhabit the desert of Western Australia. The pigeons rely almost entirely on seeds for food. . . . Confidence Intervals
# 858 :: 3/18	A questionnaire about study habits was given to a random sample of students taking a large introductory statistics class. The sample of 25 students re. . . Margin of Error
# 857 :: 3/17	A drug manufacturing company conducted a survey of customers. The research question is: Is there a significant relationship between packaging preferen. . . Chi-Square Test of Independence
# 856 :: 3/14	In this case, we are going to study some data collected from Kelly Blue Book for several hundred 2005 used General Motors (GM) cars. This data allows . . . Regression Analysis
# 855 :: 3/6	Random samples of five were selected from each of three populations. The sum of squares total was 100. The sum of squares due to the treatments was 4. . . ANOVA Summary Data
# 853 :: 3/6	A recent study focused on the number of times men and women who live alone buy take-out dinner in a month. The information is summarized below. Stat. . . 2-sample z-test
# 852 :: 3/5	There are four entrances to the Government Center Building in downtown Philadelphia. The building maintenance supervisor would like to know if the en. . . Chi-Square Goodnes of Fit Test
# 851 :: 3/5	In a particular market there are three commercial television stations, each with its own evening news program from 6:00 to 6:30 P.M. According to a r. . . Chi-Square Test of Independence, Chi-Square Goodnes of Fit Test
# 850 :: 3/5	The following is a partial ANOVA table. Source sum of Squares df . . . ANOVA Table, ANOVA
# 849 :: 3/5	A real estate agent in the coastal area of Georgia wants to compare the variation in the selling price of homes on the oceanfront with those one to t. . . F-test
# 848 :: 3/5	The president of the American Insurance Institute wants to compare the yearly costs of auto insurance offered by two leading companies. He selects a . . . Paired t-test
# 847 :: 3/5	Grand Strand Family Medical Center is specifically set up to treat minor medical emergencies for visitors to the Myrtle Beach area. There are two fac. . . 2-sample t-test
# 846 :: 3/2	A recent article in The Wall Street Journal reported that the 30-year mortgage rate is now less than 6 percent. A sample of eight small banks in the . . . 1-sample t-test
# 845 :: 3/2	Dole Pineapple, Inc., is concerned that the 16-ounce can of sliced pineapple is being overfilled. Assume the standard deviation of the process is .03. . . 1-sample t-test, 1-sample Z-test
# 844 :: 3/2	A new weight-watching company, Weight Reducers International, advertises that those who join will lose, on the average, 10 pounds the first two weeks. . . 1-sample t-test, 1-sample Z-test
# 843 :: 2/27	Braking distances of cars. A random sample of 13 four-cylinder cars is obtained and braking distances are measured and found to have a mean of 137.5 . . . Standard Deviation, Two Variances, F-statistic
# 842 :: 2/18	what statistic method is best used to test 'the influence of persons on behaviour of other persons? thank you.. . .
# 840 :: 2/11	Sat verbal scores are normally distributed with a mean of 426 and a standard deviation of 94. Use the Empirical Rule to determine what percent of the. . . Empirical Rule
# 838 :: 2/9	using the full 5-step process test to see if a population mean is not 25. Sample data is: Mean 24, standard deviation 10 and a sample of 400 was taken. . . 1-sample t-test
# 836 :: 1/13	a statistician was setting up a hypothesis test with a level of significance dictated by upper management. However, she was concerned that the test wo. . . Type II Error, Sample Size
# 835 :: 12/12/09	• Analyze the following two data sets: o In Statistics Alive, Module 35, p. 410–411, data are presented for 15 persons regarding high. . .
# 834 :: 12/9/09	You are interested in testing the hypothesis that men have greater levels of political participation than women, so you survey 332 men and 375 women . . . 2-sample t-test, Hypothesis Test
# 833 :: 12/9/09	suppose that the census indicates the average American earns $36,345.45 per year. You are interested in the whether people who majored in political s. . . Hypothesis Test, 1-sample t-test
# 832 :: 12/8/09	1.What are the underlying assumptions of Spearman rank-order scale? 2.What happens when a stanine is more than 9?Explain.. . .
# 831 :: 12/3/09	I have a humor appreciation survey with 40 items and 500 participants. The items were interpreted and classified by a theory into four classes of 10 i. . .
# 830 :: 11/24/09	A psychologist is studying the distribution of IQ scores of girls at an alternative high school. In wishing to estimate the average IQ scores in this . . .
# 824 :: 11/8/09	The grades on a statistics midterm test are normally distributed with a mean of 78 and a standard deviation of 6 a. What proportion of the class has . . . Z-Score, Standard Error of the Mean
# 823 :: 10/22/09	What is an 'effect size' ? When is it used ? Why is it used in educational research?. . . Effect Size, Cohen d
# 822 :: 10/19/09	Jeff... the previous answer was not quite the answer I was anticipating- let me restate the problem more clearly. 1. A manufacturer has a process whi. . .
# 821 :: 10/18/09	A manufacturer can typically process 176-264 devices a given period of concern. In this situation the processing event is either pass or fail. There i. . . Power, Sample Size, Effect Size, 1-Proportion Test
# 820 :: 10/17/09	An animal trainer obtained the following sample data (Table A) in a study of reaction times of dogs (in seconds) to a specific stimulus. He then selec. . . Standard Deviation, Standard Deviation on Frequency Data, Standard Deviation of Grouped Data, F-test
# 819 :: 10/15/09	For a particular sample of 50 scores on a psychology exam, the following results were obtained. First quartile = 52 Third quartile = 84 Standard dev. . . Chebyshev's Theorem, Midrange, Empirical Rule
# 817 :: 10/8/09	1) Assuming in New York 80% of women and 50% of men know where Tiffany is. At a crossing I ask pedestrians for directions to Tiffany and get these ans. . . Binomial Probability
# 815 :: 10/5/09	Shaver Manufacturing, Inc., offers dental insurance to its employees. A recent study by the human resource director shows the annual cost per employee. . . Z-Score, Area between
# 814 :: 10/4/09	in a school how is ztest used in time table ... one group that studies 7 periods a day of 45 mins each class and the other group can choose semester w. . . 2-sample z-test, 2-sample t-test
# 813 :: 10/2/09	Serum cholesterol levels were taken from a population of 10,000 college students. The results were normally distributed. Males had a mean of 195 and a. . . Z-Score, NORMSDIST
# 812 :: 10/2/09	A Tamiami shearing machine is producing 10 percent defective pieces, which is abnormally high. The quality control engineer has been checking the outp. . . BINOMDIST, Binomial Probability
# 811 :: 10/1/09	Discuss the assumptions for using a chi-square test. Research articles using and provide practical examples from the reseach to support your assumptio. . .
# 806 :: 9/7/09	Discuss how the statistical application of Pearson r is used for hypothesis testing.l Through application of the Spearman Correlation discuss what ty. . . Pearson r, Spearman Correlation
# 804 :: 8/29/09	The mean on this test is 3.5 with a standard deviation of .5. Sally scores 1.5 on this test. How many standard deviations is Sally from the mean?. . . Z-Score
# 803 :: 8/28/09	In a study, the sum of squared deviations from the mean for the sample is 12 and there are 4 participants. What is the estimated population variance?. . . Variance
# 802 :: 8/27/09	type of research where using the t statistic may be an appropriate alternative to using a z-score. . . t statistic
# 798 :: 8/19/09	Teens were asked in the MTF 2006 survey how often they think about social issues (specific issues were not identified). The bivariate table includes r. . . Chi-Square, Chi-Square Test of Independence
# 797 :: 8/15/09	The issue of how much should be spent to solve particular U.S. social problems is a complex matter, and people have diverse and conflicting ideas on t. . . Chi-Square
# 796 :: 8/13/09	Very happy Not happy at all Mean ideal number of children 3.32 2.07 Standard deviation . . . 2-sample t-test
# 795 :: 8/13/09	Data from the MTF 2006 survey reveal that 71.5% (432 out of 604) of males and 74% (562 out of 756) of females reported trying alcohol. You wonder whe. . . 2-proportion test
# 794 :: 8/10/09	A psychologist has developed a test to measure self-control. The test is normed so that it has a mean of 100 and a standard deviation of 15... The s. . . Z-Score, Percent Score, Percentile Rank, Area between
# 793 :: 8/8/09	For the total population of a large southern city, mean family income is $34000, with a standard deviation (for the population) of $5000. a. imagi. . . Z-Score
# 792 :: 8/7/09	send the standard normal table. . .
# 791 :: 8/4/09	Serum cholesterol levels were taken from a population of 10,000 college students. The results were normally distributed. Males had a mean of 195 and a. . . Z-Score
# 790 :: 7/31/09	As a condition of employment, Fashion Industries applicants must pass a drug test. Of the last 220 applicants 14 failed the test. Develop a 99 percent. . .
# 789 :: 7/31/09	A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck labeled “3 pounds.” Of cour. . .
# 788 :: 7/31/09	A recent survey of 50 executives who were laid off from their previous position revealed it took a mean of 26 weeks for them to find another position.. . .
# 787 :: 7/30/09	Below are fertility rates (average children born per woman) in 15 EU nations for 2 years. (a) Make a scatter plot. (b) Find the correlation coefficie. . . correlation coefficient , significant correlation, Pearson r
# 786 :: 7/27/09	From her firm’s computer telephone log, an executive found that the mean length of 64 telephone calls during July was 4.48 minutes with a standard de. . . 2-sample t-test
# 784 :: 7/21/09	Two manufacturing facilities produce 1280 × 1024 LED (light-emitting diode) displays. Twelve displays are chosen at random from each lab, and the num. . . Mann Whitney
# 782 :: 7/14/09	A 20-minute consumer survey mailed to 500 adults aged 25–34 included a $5 Starbucks gift certificate. The same survey was mailed to 500 adults aged 2. . . 2-proportion test
# 781 :: 7/14/09	I am to do a study that involves people whose IQ are in the normal range 70 to 130. How many people must I screen with IQ test in order to find a samp. . . Sample Size
# 780 :: 7/14/09	Dear Mr. Sauro: In reference to you article, "Calculating a Sigma Level from Task Success," I found no references to “usability” nor “task completio. . . Usability, Six Sigma
# 779 :: 7/13/09	If all the values in a set are converted to z-scores, is the shape of the distribution of the z scores will be bell shape regardless of the distributi. . . Central Limit Theorem
# 778 :: 7/12/09	200 students took a test. The scores were normally distributed. Your score was in the 60th percentile. How many people scored at or below your score?. . . Percentile
# 777 :: 7/11/09	Suppose that the quarterly sales levels among health care information systems companies are approximately normally distributed with a mean of million. . .
# 776 :: 7/8/09	Clients at a Diabetic Education Program were randomly assigned to one of two learning programs. Group A participants attended a three-day, in-class. . .
# 775 :: 7/6/09	1.-A state meat inspector in Iowa has been given the assignment of estimating the mean net weight of packages of ground chuck labeled “3 pounds.” Of c. . . Confidence Intervals
# 774 :: 7/5/09	If I'm doing a multivariate linear regression in Minitab (about 40 variables), how to restrict all coefficients positive?. . . Linear Regression
# 773 :: 7/1/09	i have problem in run multiple linear regression which faced me a problem of heteroscadecity and i want solve it using weight least squares (wls) but . . .
# 772 :: 6/29/09	A random sample of 16 pharmacy customers showed the waiting times below (in minutes). Find a 90 percent confidence interval for Î¼, assuming that the . . .
# 771 :: 6/29/09	One-fourth of the residents of the Burning Ridge Estates leave their garage doors open when they are away from home. The local chief of police estimat. . . Bayes Theorem , Conditional Probability, Tree Diagram
# 770 :: 6/29/09	Dr. Stallter has been teaching basic statistics for many years. She knows that 80 percent of the students will complete the assigned problems. She has. . . Bayes Theorem , Tree Diagram
# 768 :: 6/26/09	A multiple choice test consists of 25 questions with possible answers of a, b, c, d, and e. Estimate the probability that with random guessing, the nu. . . Binomial pmf
# 767 :: 6/24/09	IQ scores are normally distributed with a mean of 100 and a std dev of 15. If 25 people are randomly selected for an IQ test, find the probably that . . . Z-Score
# 766 :: 6/23/09	A researcher has a series of Likert-scaled items and a measure of frequency of absenteeism. He uses each of the Likert-scaled items in a separate biva. . . Correlation, Non-Linear Correlation
# 765 :: 6/23/09	A football team's season ticket sales, percentage of games won, and number of active alumni for the years 1992-2000 are given below: Year . . . Regression Analysis
# 764 :: 6/23/09	Suppose Abraham Lincoln had answered a survey questionnaire in which he indicated that he had not received a grade school diploma. The researcher foun. . . Correlation
# 763 :: 6/18/09	Finding appropriate z- and t-scores is important when constructing confidence intervals. Confidence intervals allow one to estimate important populat. . .
# 762 :: 6/18/09	Bob enjoys making candy and some friends have encouraged him to open a candy-making business. To see if the local citizens buy enough candy, Bob gath. . .
# 761 :: 6/18/09	I need to know which formulas would be used to answer these two probability questions. 1. A certain airplane has two independent alternators to prov. . .
# 760 :: 6/17/09	. You are a researcher who conducted a study of soft-drink preferences among residents in a test market prior to an advertising campaign for a new co. . .
# 759 :: 6/15/09	A sample of 25 concession stand purchases at the May 12 matinee of Spider-Man 3 showed a mean purchase of $ 7.29 with a standard deviation of $ 3.02. . . .
# 758 :: 6/15/09	To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were hande. . .
# 756 :: 6/15/09	In Dallas some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made. . .
# 755 :: 6/14/09	Interpret the following SPSS computer output for the chi-square test. Variable COMMUTE is “How did you get to work last week?” Variable GENDER is “Are. . . Chi-Square Test of Independence, SPSS
# 754 :: 6/14/09	Collapse the response categories in the following table so that it meets the assumption of the chi-square test; then perform the test. . . . Chi-Square Test of Independence
# 753 :: 6/14/09	Perform a chi-square test on the following data: (a) Regulation is the best way to ensure a safe workplace. . . .
# 752 :: 6/14/09	An Excel Spreadsheet is reprinted below. Interpret the t-test results. Are they statistically significant? t-Test: Paired Two Sample for Means Be. . . Paired t-test
# 751 :: 6/14/09	The managers in a company’s East and West regions were rated on the basis of the company’s evaluation system. A researcher wishes to conduct a t-test . . . 2-sample t-test
# 750 :: 6/14/09	Test the hypothesis of no differences for average payback period (years) necessary to justify solar heating systems for residences. Savings and Loa. . .
# 749 :: 6/14/09	A personnel manager has a computer-generated list of all employees that indicates that 70 percent are full-time employees, 20 percent are part-time em. . . Chi-Square Goodnes of Fit Test
# 748 :: 6/14/09	What test of differences is appropriate in each of the following situations? Why? (a) Average campaign contributions of Democrats, Republicans, and. . .
# 747 :: 6/13/09	A random sample of 46 observations was selected from a normally distributed population. The sample mean was xbar=81, and the sample variance was s2=3. . .
# 746 :: 6/12/09	a. Select a variable. Compare the mean of the variable for a sample of 30 for one group with the mean of the variable for a sample of 30 for a second . . .
# 745 :: 6/8/09	Calculate the average student score necessary for the district to retain its federal funding. You may assume that the Standard Deviation will not chan. . .
# 744 :: 6/6/09	Quality Motors is an automobile dealership that regularly advertises in its local market area. It claims that a certain make and model of car averages. . . 1-sample t-test
# 743 :: 6/6/09	Assume you have the following data: Ho: u = 2,450, S = 400, n = 100, and X = 2,300. Conduct a hypothesis test at the .01 significance level. **If the. . . 1-sample Z-test
# 741 :: 6/6/09	Assume you have the following data: Ho: u = 200, S = 30, n = 64, and X = 218. Conduct a hypothesis test at the .05 significance level.. . . 1-sample Z-test
# 740 :: 6/6/09	After a bumper crop, a mushroom grower hypothesizes that mushrooms will remain at the average wholesale price of $1 per pound. State the null hypothes. . .
# 739 :: 6/4/09	How many data do we need as a minimum in order to calculate the z-score meaningfully?. . . Z-Score
# 738 :: 6/4/09	What value would be needed to complete the following probability distribution? x p (x) 0 . . . Random Variable, Expected Value
# 737 :: 5/31/09	(a) Choose one beverage category and plot the data (MILK CATAGORY CHOSEN). (b) Describe the trend (if any) and discuss possible causes. (c) Would a f. . . Time-Series
# 736 :: 5/28/09	A student heard that the average household watches 26.4 hours of t.v. per week, with a stand.dev. of 2.3 hours. He decided to run his own experiment . . . 1-sample Z-test
# 735 :: 5/25/09	how does a confidence interval this relate to learning statistics How do you think confidence intervals are useful in the real-world?. . . Confidence Intervals
# 733 :: 5/24/09	The data in the following tables are some of the results of an Internal Revenue Service survey of taxpayers. Analyze and interpret the data. -The las. . .
# 732 :: 5/23/09	You have asked to research the high absenteeism rate in your company. One required analysis is to be by gender. Assume you have been asked to do the . . .
# 731 :: 5/23/09	Test to see if four population means are the same or different. Assume the populations are normally distributed and have equal variances. Use the fo. . . ANOVA Summary Data
# 730 :: 5/23/09	Describe the steps in formal hypothesis testing. Make at least one comment for each step.. . . Steps in Hypothesis Test, Hypothesis Test
# 729 :: 5/23/09	I want to prove that a population mean is not 150. Use an alpha of 5% and set up the full, detailed, five step hypothesis test. Assume when the sampl. . . 1-sample t-test
# 728 :: 5/23/09	What hypothesis testing model (my “models” handout) would be used under each of the following conditions. Use the “model number” from my handout if y. . . Statistical Model, test statistic
# 727 :: 5/23/09	Interpret the following table showing the percentage of individuals on a low-fat or low-cholesterol diet by gender and age. Age Group Women. . .
# 723 :: 5/5/09	Using this research question and data, perform a nonparametric hypothesis test (Part A and B). Research Question: Is the average age greater than 4. . . Sign Test, Mann Whitney
# 722 :: 5/5/09	What is the definition of an "independent" variable? A dependent variable? What about a variable I intend to use to help do some forecasting. Int. . . Scatter Plot, Scatter Diagram, Independent Variable, Dependent Variable
# 721 :: 5/5/09	What does regression do? What is its purpose?. . . Regression Analysis
# 720 :: 5/5/09	City Opera, a local opera company, wishes to take a sample of its subscribers to learn the average number of years people have been subscribing. The d. . . Sample Size
# 718 :: 5/5/09	The state of Texas college admission board has set a standard for automatic acceptances to any university at top 10% of any graduating class will be a. . . Z-Score
# 716 :: 5/5/09	The rockets are playing Lakers tonight in basketball. The lakers average 90 points a game, with a SD of 10. What would the rockets need to score to be. . . Z-Score
# 715 :: 5/5/09	university of texas will accept all students that have a GPA in the top 10% at their school. At yates the school GPA average is 3.0(on a 4.0 scale) wi. . . Z-Score
# 714 :: 5/5/09	The mean score on a math test at milby high school was 50. the standard deviation was 10. If the same test was administered to the entire school distr. . . Z-Score
# 713 :: 5/3/09	Do students at various colleges differ in how sociable they are? Twenty-five students were randomly selected from each of three colleges in a particul. . . ANOVA, Eta-Squared, Effect Size, ANOVA Summary Data
# 712 :: 5/3/09	Make up a scatter diagram with 10 dots for each of the following situations: (a) perfect positive linear correlation, (b) large but not perfect positi. . . Scatter Diagram, Correlation, Curvilinear Correlation
# 711 :: 5/3/09	Four research participants take a test of manual dexterity (high scores mean better dexterity) and an anxiety test (high scores mean more anxiety). Th. . .
# 710 :: 4/30/09	Discuss how the statistical application of Pearson r is used for hypothesis testing. Through application of the Spearman Correlation discuss what typ. . . Correlation, Pearson r, Spearman Correlation
# 709 :: 4/30/09	Discuss which analysis of variance should be applied when an experiment has more than one independent variable. Discuss the assumptions and limitation. . . ANOVA, Factorial ANOVA, 2-Way ANOVA
# 708 :: 4/30/09	Standardized scores offers a way of comparing norm-referenced scores. The z-score distribution is based on knowing how many standard deviations away f. . . Z-Score, t-score, Percentile Rank
# 707 :: 4/29/09	Would you be able to assist me in completing a 5 step hypothesis test on both hypotheses (1 parameter & another with 2 or more)? In completing this t. . . Five Step Hypothesis Testing, Parameter
# 706 :: 4/28/09	What is a chi-squared test used for? What is the typical null and alternate hypothesis when doing a chi-squared test?. . . Chi-Square
# 705 :: 4/27/09	THIS QUESTION IS NO LONGER AVAILABLE. . . 1-sample Z-test
# 703 :: 4/26/09	The following data is a random sample of 1st quiz scores from previous Research 342 classes. 9.5, 6.5, 4.25, 8.5, 7.5, 4.5, 4.25, 6, 7 mean = 6.44 . . . Confidence Intervals
# 702 :: 4/26/09	A random sample of 100 students who took a statistics exam were asked their score on the exam. The mean score on the test was 50; the standard deviat. . . Z-Score, Area between
# 701 :: 4/26/09	A local bakery determines that the probability of a customer ordering a blueberry muffin is 50%. 5 customers come into the bakery. A. What is the pr. . . BINOMDIST, Binomial pmf, Binomial Probability
# 700 :: 4/26/09	2) Assume the following summary statistics, which describe the speed of a computer processor, are available from a sample of Intel Pentium IV chips ma. . . Chebyshev's Theorem
# 699 :: 4/26/09	1) The following are the first Quiz scores from a previous RES 341 class: 9.5, 7.5, 9.5, 7, 10, 7.5, 6.5, 1.5, 8, 10 A. Is this data discrete or co. . . Continuous Data
# 698 :: 4/26/09	A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087. . .
# 697 :: 4/25/09	A random sample of 30 executives from companies with assets over $1 million was selected and asked for their annual income and level of education. Th. . . ANOVA, Seasonal Data
# 695 :: 4/24/09	I need help with the following. (A) Develop one business research question (B) Formulate a research hypothesis to test one population parameter an. . . Parameter
# 694 :: 4/21/09	Suppose you conduct a study and find that the probability of having a baby boy is 60%. Now suppose three of your relatives are going to have babies. . . .
# 693 :: 4/21/09	Given a single deck of cards, what is the probability of drawing either a king or a diamond? Hint - There are four kings in a deck and 13 diamonds. T. . . Union, Probability, Joint Probability
# 692 :: 4/21/09	Create a Histogram of the following data: Interval Frequency 0 - 5 0 5 - 10 5 10 - 15 5 15 - 20 15 20 - 25 5 25 – . . .
# 691 :: 4/21/09	Calculate the Standard Deviation of the following list of data: 6, 7, 8, 9, 10. . . Standard Deviation
# 689 :: 4/20/09	Accounting procedures allow a business to evaluate their inventory at LIFO (Last In First Out) or FIFO (First In First Out). A manufacturer evaluated. . . Paired t-test
# 687 :: 4/18/09	I would like to determine whether Meijer or Kroger has lower prices on average for families. I randomly speak with 100 customers who are purchasing g. . . Independent Sample
# 686 :: 4/18/09	A label on a container of orange juice claims that the orange juice contains an average of 2 grams of fat with standard deviation of 1.5 grams. A cons. . . 1-sample Z-test
# 685 :: 4/18/09	NKU needs to estimate the mean number of hours that all students work to earn money, on average, per week during the full semesters (fall and spring).. . . Sample Size, Margin of Error
# 684 :: 4/18/09	Tax companies imply that the returns they prepare are perfect, but what proportion of returns from tax companies have mistakes? To answer this questio. . . Confidence Intervals, Confidence Interval around a Proportion
# 683 :: 4/18/09	A baseball fan would like to estimate the mean time it takes to complete a major league baseball game. He randomly selects 40 game lengths (times to c. . . Confidence Intervals
# 682 :: 4/17/09	Explain the difference between testing a single mean and testing the difference between two means. What two assumptions must be met when one is using . . . Difference between means
# 681 :: 4/17/09	If two independent samples are used in a hypothesis test concerning the difference between population means for which the combined degrees of freedom . . . Degrees of Freedom
# 680 :: 4/17/09	To test the null hypothesis that the mean waist size for males under 40 years equals 34 inches versus the hypothesis that the mean differs from 34, th. . . test statistic
# 679 :: 4/17/09	State the null hypothesis, Ho,and the alternative hypothesis, Ha , that would be used to test the claim: The standard deviation has increased from its. . . Null Hypothesis , Alternative Hypothesis
# 678 :: 4/17/09	A particular candidate claims she has the support of at least 60% of the voters in her district. A random sample of 150 voters yields 87 who support h. . . test statistic, Normal Approximation to Binomial
# 677 :: 4/17/09	A random sample of 51 observations was selected from a normally distributed population. The sample mean was x = 88.6 , and the sample variance was s2 . . . Chi-Square, Standard Deviation, Population Standard Deviation, sample variance, sampe standard deviation
# 676 :: 4/17/09	Consider testing Ho: μd ≤ 0 vs. Ha: μd = > 0 with n =20 and t∗ =1.95. Place bounds on the p-value using the table of “critical. . . Student-t, Student’s t-distribution, Critical Value
# 675 :: 4/17/09	A group of sheep, infested with tapeworms, are randomly divided into two groups as follows. Each sheep is assigned a number (1 through 20) and then 10. . . Dependent Sample, Independent Sample
# 674 :: 4/17/09	In what ways is the t distribution similar to the standard normal distribution? In what ways is the t distribution different from the standard normal . . . t-distribution, Standard Normal Distribution
# 673 :: 4/16/09	Classify the following as independent or dependent samples: a. Weights of identical twins b. The effectiveness of two different brands of ibuprofen. . . Dependent Sample, Independent Sample
# 672 :: 4/13/09	In Meijer supermarket, the customer's waiting time to check out is approximately normally distributed with a standard deviation of 2.5 minutes. A samp. . . Hypothesis Test
# 671 :: 4/13/09	A statistician was testing the following hypotheses: Ho: μ = 500 vs. Ha: μ ≠ 500. The p-value approach was to be used. A sample . . .
# 670 :: 4/13/09	Assume that z is the test statistic and calculate the value of z∗ for testing the null hypothesis Ho: μ =150.0 when σ = 4.5, n=15, x(b. . . test statistic, z-test
# 669 :: 4/13/09	You have failed to reject the null hypothesis when it is false, and therefore you have made a A) Type A correct decision. B) Type B corr. . . Type I Error, Type II Error, Hypothesis Test
# 668 :: 4/13/09	Which of the following is the probability of making a Type I error? A) α B) 1 - α C) β D) 1 - β. . . Type I Error, Type II Error
# 667 :: 4/11/09	If the p-value is greater than the level of significance α , then the decision must be to reject Ho. A) True B) False. . . p-value, Hypothesis Test
# 664 :: 4/11/09	If our decision in a hypothesis test is to fail to reject the null hypothesis, then we know that the null hypothesis must be true. A) True . . . Null Hypothesis
# 663 :: 4/11/09	When we reject the null hypothesis, we are certain that the null hypothesis is false. A) True B) False. . . Null Hypothesis
# 662 :: 3/23/09	I need the formula to calculate z-score. My input is: Base Sample Size, Target Sample Size, Base Proportion, Target Proportion. I have a calculator . . . 2-proportion test
# 661 :: 3/19/09	A student is taking a 10 question multiple choice quiz. There are four possible answers to each question. The student decides to guess at random on al. . . BINOMDIST
# 660 :: 3/18/09	Four cards are selected, one at a time, from a standard deck of 52 cards. Let x represent the number of aces drawn in a set of 4 cards. If this expe. . . Binomial Probability
# 659 :: 3/18/09	Suppose that A and B are mutually exclusive events, and that P(A) = 0.4 and P(B) = 0.3. Then, P(A and B) will be: A) 0.0 B) 0.4 C) 0.3 D) 0.7. . .
# 658 :: 3/18/09	Under certain conditions, it is possible that the sum of the probabilities of all the sample points in a sample space is less than one. A) Tru. . .
# 657 :: 3/18/09	If events A and B are not mutually exclusive, they may be either independent or dependent. A) True B) False. . .
# 653 :: 3/11/09	What is the cost of a telephone call (per dollar) using a calling card that follows the formula below for a 20-minute call. Cost = 0.50 + 0.15 Minute. . .
# 651 :: 3/9/09	For a population with a mean of 80 and standard deviation of 12, what is the z-score corresponding to x=71?. . .
# 650 :: 3/9/09	2. Your company makes ice cream (178 flavors!) and has just acquired a distribution company with lots of ice cream trucks. You will use their trucks. . .
# 648 :: 3/7/09	A financial planner wants to compare the yield of income- and growth-oriented mutual funds. Fifty thousand dollars is invested in each of a sample of. . .
# 644 :: 3/3/09	An aptitude test has a mean of 220 and standard deviation of 10. find the corresponding z score for: a) a test score of 232 b) a test score of 212. . . Z-Score
# 642 :: 3/2/09	You are a purchasing agent at a major manufacturing company. You have several hundred business cards from sales reps who have visited you, and you ha. . .
# 641 :: 3/2/09	In general, what is a “Critical Value” or “Cut-Off Score” of a test statistic. . . Critical Value, test statistic
# 639 :: 2/28/09	CherryBerry Soda, Inc. claims that 15 percent of the population can identify its products. In efforts to boost their identity, CherryBerry employs a f. . . Normal Approximation to Binomial , 1-Proportion Test
# 638 :: 2/23/09	To test the null hypothesis that the mean waist size for males under 40 years equals 34 inches versus the hypothesis that the mean differs from 34, th. . . 1-sample t-test
# 637 :: 2/22/09	Hi Jeff thanks for all your help so far, your answers have been great and very timely. It is great to be able have help from someone with great profes. . . Adjusted Wald, Confidence Intervals
# 635 :: 2/22/09	Linemarking for parking bays shall be determined by the retroreflectivity performance of glass beads in the linemarking. The linemarking average level. . . 1-sample t-test, Confidence Intervals
# 634 :: 2/20/09	A contractor is responsible for drainage network cleaning and shall ensure that the required level of service is achieved. The required level of servi. . . 1-Sample Proportion Test
# 633 :: 2/20/09	Roadmarking shall be determined by the retroreflectivity performance of glass beads in the road marking. The roadmarking average level of reflectivity. . .
# 632 :: 2/19/09	An automobile manufacturer wants to estimate the mean gasoline mileage that its customers will obtain with its new compact model. How many sample runs. . . Sample Size, Margin of Error
# 631 :: 2/19/09	My company has been arguing over this topic for quite a while, and I'm looking to put an end to this mathematical question. We are an ad agency who. . . A/B Testing, Response Rates
# 630 :: 2/19/09	Pretend that you are a Finance person in a large dynamic company. Your dream is to become CFO someday, so you want to make good financial decisions. Y. . .
# 629 :: 2/17/09	The following data show samples of three chain stores in three different locations in one town and the amount of dollars spent per customer per visit.. . . ANOVA
# 628 :: 2/16/09	I have a standard normal distribution with Mean 130, Stdev 8 for school X and a normal distribution for 120 and 10 for school Y. If we select 1 studen. . .
# 627 :: 2/16/09	I have two questions. Thanks for answering them. (1)A sports enthusiast created an equation to predict Victories (the team’s number of victories in. . .
# 626 :: 2/15/09	Greetings, My name is Dave Thompson and I work with the Conasauga Drug Court Treatment program in Dalton, GA. I am a Field Practicum Instructor f. . .
# 625 :: 2/11/09	Mean output of solar cells of three types are measured six times under random light intensity over a period of 5 minutes, yielding the results shown. . . . ANOVA
# 623 :: 2/9/09	The following table lists the number of U.S. mainland hurricane strikes (from 1900 to 1996) for various intensities according to the Saffir-Simpson Hu. . . Random Variable, Probability Distribution
# 622 :: 2/9/09	1. If the daily stock price, x, of United Technology is normally distributed with mean 6.56 and standard deviation 2.4, calculate the probability that. . .
# 621 :: 2/8/09	Consider a sample with data values of 10,20,12,17, and 16. Compute the z-score for each of the five observations. . . Z-Score
# 620 :: 2/8/09	The total area under the curve of the standard normal distribution is not necessarily 1.0. A) True B) False. . . Normal Curve, Standard Normal Distribution, Standard Normal Curve
# 619 :: 2/8/09	Suppose the annual consumption of chicken mean is 20.84 pounds per person, and that the standard deviation for the consumption of chicken per person i. . . Central Limit Theorem
# 618 :: 2/8/09	Individual scores of a placement examination are normally distributed with a mean of 84.2 and a standard deviation of 12.8. If a random sample of s. . . Z-Score, t-score
# 616 :: 2/7/09	Evolutionary theories often emphasize that humans have adapted to their physical environment. One such theory hypothesizes that people should spontane. . . 1-sample t-test
# 613 :: 2/7/09	I am confused on how to calculate a z-score. I am doing a six sigma project right now and am lost on doing the z-score. Here is the information I am p. . . Z-Score
# 611 :: 2/5/09	6.) For the following set of data, find the linear regression equation for predicting Y from X: X Y 0 9 . . . Regression Equation
# 600 :: 1/30/09	True or False The moving average method averages out cyclical and irregular components. When using Chi Square , the sum of the expected freque. . . ANOVA, Chi-Square, Goodnees of Fit, F distribution
# 599 :: 1/30/09	There are two major tests of readiness for college, the ACT and the SAT. ACT scores are reported on a scale from 1 to 36. The distribution of ACT scor. . . Z-Score, SAT Scores, ACT Scores
# 597 :: 1/30/09	TRUE OR FALSE 1. ANOVA is used when we want to know if more than two population means are equal. 2. The sum of the squares error measures the vari. . . ANOVA
# 589 :: 1/26/09	Apply the Law of Large Numbers: Explain how the following scenario is possible using a coin toss and fictitious data: As the number of trials increase. . . Law of Large Numbers
# 588 :: 1/26/09	An aptitude test has a mean of 220 and standard deviation of 10. find the corresponding z score for: a) a test score of 232. . . Z-Score
# 587 :: 1/26/09	True or False Generally speaking, the Null Hypothesis is set up for the purpose of either accepting or rejecting it. If the Null Hypothesis is fal. . . Null Hypothesis , Alternative Hypothesis
# 581 :: 1/21/09	hi, I hope you can help me ? I have 30 variables that i wanted to sort them under 5 known groups . the data came from interviews where i collected . . .
# 580 :: 1/21/09	Conduct the equivalent, nonparametric test of hypothesis using the 5-step process. MLB ï¿½ Higher Salaries equate to more home runs per team (Using . . .
# 576 :: 1/16/09	TRUE or FALSE The level of significance is the probability that a true hypothesis is rejected. A Type one error is also referred to as an alpha r. . . Hypothesis Test, Alternative Hypothesis , Alpha, Null Hypothesis
# 574 :: 1/14/09	Assume you have the following data: Ho mu = 200, s = 30, n = 64, and x-bar = 218. Conduct a hypothesis test at the .05 significance level. Assum. . . 1-sample t-test, 1-sample Z-test
# 572 :: 1/13/09	At one university, students are given z-scores at the end of the semester rather than the traditional GPAs. The mean and standard deviation of all stu. . . Empirical Rule, Z-Score
# 571 :: 1/10/09	Dr Zak developed a test to measure depression. He sampled 100 university students to take his five item test. The group of students was comprised of 3. . . Z-Score, Standard Score
# 570 :: 1/7/09	How can a t test be employed in hypothesis testing by the use of directional versus nondirectional hypothesis. . . directional test, 1-tailed test
# 569 :: 12/21/08	Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are all. . . 1-sample t-test, TDIST
# 568 :: 12/21/08	16 (a) Plot the data on U.S. general aviation shipments. (b) Describe the pattern and discuss possible causes. (c) Would a fitted trend be helpful? Ex. . . Trend Line, Linear Regression
# 566 :: 12/19/08	In an ANOVA test there are 5 observations in each of three treatments. The degrees of freedom in the numerator and denominator respectively are: a. . . . ANOVA, Degrees of Freedom
# 565 :: 12/19/08	The coefficient of correlation between two variables X and Y was computed to be ƒ{0.60. This means a. the coefficient of determination is 0. b. a. . . Correlation, coefficient of determination
# 564 :: 12/19/08	For each of the following situations, indicate whether an error has occurred and, if so, indicate what kind of error (Type I or Type II) has occurred.. . . Type I Error, Type II Error, Power, Hypothesis Test
# 563 :: 12/19/08	A vinyl siding company claims that the mean time to install siding on a medium-size house is at most 20 hours with a standard deviation of 3.7 hours. . . . 1-sample Z-test, 1-sample t-test
# 562 :: 12/17/08	Why does the main factor MSs in 2 way ANOVA sometimes carry along interaction effect?. . . ANOVA, 2-Way ANOVA
# 560 :: 12/17/08	Throughout history 55% of registered voters actually have cast a ballot. What is the probability that among a group of 28 students who are registered. . . BINOMDIST, Binomial cdf, Compliment Rule
# 559 :: 12/16/08	The serum cholesterol levels for men in one age group are normally distributed with a mean of 185.1 and a standard deviation of 37.8. All units are i. . . Area between, Z-Score
# 558 :: 12/16/08	If Z is a standard normal variable, find the probability that z lies between 0.73 and 1.88 or P(0.73 Area between, Z-Score
# 557 :: 12/16/08	Find the margin or error for the 95% confidence interval used to estimate the population proportion. In a survey of 7100 TV viewers, 38% said they wa. . . Confidence Intervals, Margin of Error
# 555 :: 12/14/08	Complete the following: a. Select a variable. Compare the mean of the variable for a sample of 30 for one group with the mean of the variable for a . . . 2-sample t-test, 2-proportion test, 2-sample z-test, z-test
# 551 :: 12/12/08	Philadelphia is conducting a study on the characteristics of tourists who drive to Eagles football games. Previous studies indicate that approximately. . . Sample Size, Confidence Intervals, Proportion
# 550 :: 12/12/08	Jeff, I am working Trend lines for yearly data and I can't figure this step: trend line is Tt=22.6+0.45 t to generate yearly forecast. Trend line beg. . . Trend Line
# 549 :: 12/10/08	An expert witness in a case of alleged racial discrimination in a state university school of nursing introduced a regression of the determinants of Sa. . . Regression Equation, Regression Analysis
# 548 :: 12/10/08	A researcher used stepwise regression to create regression models to predict BirthRate (births per 1,000) using five predictors: LifeExp (life expecta. . . Stepwise Regression, Regression Analysis
# 546 :: 12/10/08	In the following regression, X = total assets ($ billions), Y = total revenue ($ billions), and n = 64 large banks. (a) Write the fitted regression eq. . . Regression Analysis, Slope, Regression Equation
# 545 :: 12/10/08	In the following regression, X = weekly pay, Y = income tax withheld, and n = 35 McDonald’s employees. (a) Write the fitted regression equation. (b) S. . . Regression Analysis, Slope
# 544 :: 12/10/08	(a) How does correlation analysis differ from regression analysis? (b) What does a correlation coefficient reveal? (c) State the quick rule for a sign. . . Correlation, correlation coefficient , Regression Analysis, significant correlation
# 542 :: 12/9/08	A financial analyst wants to compare the turnover rates, I percent, for shares of oil-related stocks versus other stocks, such as GE and IBM. She sele. . . 2-sample t-test, Unequal Variances
# 541 :: 12/9/08	A stockbroker at Critical Securities reported that the mean rate of return on a sample of 10 oil stocks was 12.6 percent with a standard deviation of . . . F-test, Homogeneity of Variance, Unequal Variances, Levine test
# 540 :: 12/9/08	A sample of 36 observations is selected from a normal population. The sample mean is 21, and the sample standard deviation is 5. Conduct the following. . . 1-sample t-test, 1-tailed test, Null Hypothesis , calculating mean, sample variance, Standard Deviation
# 539 :: 12/9/08	The following sample observations were randomly selected X: 5 3 6 3 4 4 6 8 Y: 13 15 7 12 13 11 9 5 Determine the coefficient of correlati. . . Correlation, coefficient of determination
# 538 :: 12/9/08	When would it be appropriate to use ANOVA and when is it appropriate to use a paired t test? Be specific and give examples.. . . ANOVA, Paired t-test
# 537 :: 12/6/08	Can people really identify their favorite brand of cola? Volunteers tasted Coca-Cola Classic, Pepsi, Diet Coke, and Diet Pepsi, with the results shown. . . 2-proportion test, Chi-Square
# 536 :: 12/6/08	High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this hazard for many hours. A Boeing 727 co-pilot coll. . . Chi-Square, CHIDIST
# 535 :: 12/6/08	A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question:. . . Chi-Square, CHIDIST
# 534 :: 12/6/08	Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain they were about. . . Chi-Square, CHIDIST
# 533 :: 12/6/08	I need help on understanding multiple logistic regression, especially inference, goodness-of-fit, and calculating Likelihood Ratio Chi-Square using G^. . .
# 532 :: 12/5/08	Based on the genotypes of parents, offspring are expected to have genotypes distributed in such a way that 25% have genotypes denoted by AA, 50% have. . . Chi-Square, Goodnees of Fit
# 531 :: 12/4/08	What is higher a z score of .500 or a raw score of 17. . .
# 530 :: 12/2/08	What score would it have taken to be in the 90th percentile in a test with a mean of 40 and standard deviation of 7. . . Z-Score, Percent Score
# 528 :: 11/28/08	In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the resulting damage (in dollars) was estimated. Five te. . . ANOVA
# 527 :: 11/28/08	A sample of 25 concession stand purchases at the October 22 matinee of Bride of Chucky showed a mean purchase of $5.29 with a standard deviation of $3. . . Homogeneity of Variance, F-test, Levine test
# 526 :: 11/28/08	To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were hande. . . 2-sample t-test, Homogeneity of Variance, Equal Variances, F-test, Levine test
# 525 :: 11/28/08	Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave lovastatin to 2,325 people and an i. . . 2-proportion test, Normal Approximation to Binomial
# 524 :: 11/24/08	Discuss how t test can be employed in hypothesis testing by the use of directional vs. nondirectional hypotheses. Discuss types of research where usi. . . t-score, Z-Score, directional test, nondirectional test, 1-Sided Test
# 523 :: 11/24/08	Use the given degree of confidence and sample data to construct a confidence interval for the population mean x. Assume that the population has a norm. . . Confidence Intervals, TINV
# 521 :: 11/24/08	The width of a confidence estimate for a proportion will be: a. Narrower for a 99% confidence interval than for a 95% confidence interval. b. Wider . . . Confidence Level, Confidence Intervals, Proportion
# 520 :: 11/23/08	Your company asks you to compare a new advertising campaign and the old one. Sample data on the accounts as follows: Old: 40, 28, 35, 38, 31, 42, 26,. . . Confidence Intervals, Median, Mode, mean, t-statistic, Standard Error of the Mean
# 519 :: 11/23/08	Fill in the P (X=x) values in the table to give legitimate probability distribution for the discrete random variable X, whose possible values are -4, . . . Random Variable, Probability, Compliment Rule
# 517 :: 11/22/08	An executive drives his vehicle from home to work daily. Driving times are normally distributed with a mean of 35 minutes and standard deviation of 8. . . Z-Score, Area between, above .10
# 516 :: 11/19/08	Given a mean score of 70, standard deviation of 15,percentile of 23.Find the Z score,T score and raw score. Please explain how to work backward on a . . . T score, Percent Score, Z-Score
# 515 :: 11/19/08	I run various A/B Split tests online. I always set all my tests for 10,000 visitors so page A and B are each equally rotated 5,000 times. My problem. . . 2-proportion test, Normal Approximation to Binomial , Power, A/B Testing
# 514 :: 11/17/08	I am trying to assess the impact of an event on a population. I ran a survey before the event and then I ran the survey after the event. The collect. . . Paired t-test, Within Subjects, 1-Sided Test, One-Tailed Test
# 513 :: 11/17/08	I have a question about SEYhat in time-series regression for N=1 subject.... I want to know whether the StdError of the fitted score (SEYhat) can. . . Time-Series, Regression Analysis, autocorrelation
# 512 :: 11/14/08	When estimating the mean of a population, how large must the sample be in order that the 95% error margin is 1/8 the standard deviation?. . . Sample Size, Margin of Error, Standard Deviation, Standard Error of the Mean
# 511 :: 11/13/08	A machine produces 3 inch nails. A sample of 100 nails is selected, and it is found that 25 are shorter than 3 inches. Find the 95% confidence interv. . . Proportion, Confidence Intervals, One-Tailed Area
# 510 :: 11/13/08	Survey to determine what proportion of new car buyers continue to have their car serviced at the dealership after warranty ends. Estimates 30% of cust. . . Sample Size, Confidence Level
# 509 :: 11/13/08	A researcher expects the population proportion of the Cubs Fans in Chicago to be 80%. Error of less than 5% confident of an estimate to be made from a. . . Confidence Intervals, Sample Size, Margin of Error
# 508 :: 11/13/08	In a national wide survey a researcher expects 30 percent of the population will agree with an value statement. He wishes to have less than 2% error a. . . Sample Size, Margin of Error, Confidence Level
# 507 :: 11/12/08	In a survey of 500, 60% responded positively to an value question. Calculate a confidence level at 95% to get an interval estimate for proportion?. . . Sample Size, Confidence Intervals, Proportion
# 506 :: 11/12/08	Suppose you are planning a sample of employees to determine the monthly average # of vacation days. Standards set: Confidence level of 99% and an erro. . . Sample Size, Margin of Error, Confidence Intervals
# 505 :: 11/11/08	Calculate a 98% confidence interval for the following data 15.7,15.7,15.5,15.2,15.2,15.1,15.3.. . . Confidence Intervals, TINV, Margin of Error, t-statistic
# 504 :: 11/9/08	Calculate the 95% confidence interval on the following GPA's from 30 randomly selected students. 0.979 0.891 0.962 0.858 0.909 0.936 0.963 0.9. . . Confidence Intervals, Margin of Error, t-statistic
# 503 :: 11/7/08	Choose a variable and collect data for at least three different groups (samples). Compare the means of the three groups using the one-way ANOVA techni. . . ANOVA, F-statistic
# 502 :: 11/7/08	Administrative staff based at a business school in the UK are advised to take a 15 minute break from their personal computer after working on it for 9. . . Confidence Intervals, TDIST, t-test, Z-Score
# 501 :: 11/7/08	In a survey of adults, 68% thought that DNA test for identifying an individual were very reliable. You randomly select 24 adults and ask each if he or. . . BINOMDIST, Binomial Probability, Continuity Correction, Normal Approximation, Normal Approximation to Binomial
# 500 :: 11/7/08	In a recent year grade 8 Washington State public school students taking a mathematics assessment test had a mean score of 276.1 with a standard deviat. . . Percent Score, Area between, Z-Score
# 499 :: 11/7/08	A newspaper finds that the mean number of typographical errors per page is five. Find the probability that: a. Exactly five typographical errors will. . . Poisson, Poisson Distribution
# 498 :: 11/7/08	During the next hour, five customer arrivals are expected. What is the probability that more than five customers will show up (according to the Poisso. . . Poisson, Poisson Distribution
# 497 :: 11/6/08	A random sample of n=64 children of working mothers showed that they were absent from school an average of 5.3 days per term, with a standard deviatio. . . Confidence Intervals, Confidence Level
# 495 :: 11/4/08	The EPA range for a car is 20-28mpg, how large of a sample would be required to estimate your mean mpg with an error of +/- 1 mpg with 90% confidence. . . Sample Size
# 494 :: 11/4/08	If the average price of a new home is 145,000 what is the minimum and maximum prices of the houses a contractor will need to build to include the midd. . . Z-Score, Area between
# 493 :: 11/4/08	On a police sergeants exam, the historical mean scored was 80 with a standard deviation of 20. Four offiers scored 195,175,191, and 189 respectively. . . . Empirical Rule, Z-Score, Unusual Event, Percent Score
# 492 :: 11/3/08	if an eligible couple on an average has 3.3 children then the birth rate will be?. . .
# 491 :: 10/30/08	Using continuity Correction. There are many situations in which a normal distribution can be used as a good approximation to a random variable that ha. . . Continuity Correction
# 487 :: 10/28/08	Find a confidence interval for the mean assuming that each sample is from a normal population. Mean = 127, s = 27, n = 16. Find the 90% Confidence Int. . . TINV, t-distribution, Confidence Intervals
# 486 :: 10/28/08	1.A telescope manufacturer wants its telescopes to have standard deviations in resolution to be significantly below 2 when focusing on objects 500 lig. . .
# 485 :: 10/27/08	Assume that the heights of 5 year old boys are normally distribued with a mean of 100cm and a standard deviation of 60. What is the sampling distribut. . . TINV, Confidence Intervals, Standard Error of the Mean, Standard Deviation of the Mean
# 484 :: 10/25/08	With a normal distribution of 50 and standard deviation of population =10, how do I figure out the score at the 40th percentile? How do I figure out t. . . Z-Score, Area between, Percent Score
# 483 :: 10/21/08	I have a research study where we have a "test" and a "control" group. We calculated a market share percentage for both groups, the test group was in . . . McNemar Chi-Square , Chi-Square
# 482 :: 10/20/08	a telescpoe manufacturur wants its telescopes to have standard deviations in resolution to be significantly below 2 when focusing on objects 500 light. . .
# 481 :: 10/20/08	a centre university has a student population of 60000. the university is interested in determining what proportion of them is in favour of a new gradi. . .
# 476 :: 10/13/08	Does normal distribution is something to do with Altman Z-Score?. . . Altman Z-Score, Z-Score
# 475 :: 10/12/08	A telephone manufacturer wants its telescope to have standard deviation in resolution to be significantly below 2 when focusing on object 500 light-ye. . . Standard Deviation, Chi-Square, Chi-Square Distribution
# 474 :: 10/12/08	The central university has a student population of 60000. The university is interested in determining what proportion of them is in favour of a new gr. . .
# 471 :: 10/9/08	A central university has a student population of 60,000. The university is interested in determining what proportion of them is in favour of a new gra. . . Margin of Error, Confidence Intervals, Sample Size
# 470 :: 10/9/08	A telescope manufacturer wants its telescopes to have standard deviations in resolution to be significantly below 2 when focusing on objects 500 light. . . Chi-Square Distribution, Confidence Intervals, Standard Deviation, Variance
# 469 :: 10/8/08	Mean output of solar cells of three types are measured six times under random light intensity over a period of 5 minutes, yielding the results shown. . . .
# 467 :: 10/7/08	The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If 485 out of the next 500 o. . . 1-Proportion Test, Normal Approximation
# 466 :: 10/7/08	Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn counted 773 kernels and put them in a popp. . .
# 465 :: 10/7/08	A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages On each page, the mean area d. . .
# 464 :: 10/7/08	How do you know when to use a t-score instead of a z-score and vice versa?. . . Z-Score, t-score
# 463 :: 10/6/08	Find the probability of correctly answering the first 2 questions on a multiple choice test if random guesses are made and each question has 3 possibl. . . Multiplication Rule
# 462 :: 10/6/08	Olympic Track related question: You know the last 5 race times at the same distance for 8 runners competing in a race. As such, you can calculate the. . . Z-Score
# 461 :: 10/6/08	My question is on Measurement system analysis (MSA). My metric is lead time. I calculated it from the system (computer database) which stores all th. . . Gage R&R
# 460 :: 10/5/08	20% kids danced. If 10 were selected at random, find probability that exactly four danced.. . . BINOMDIST, Binomial pmf
# 459 :: 10/5/08	How do you calculate a participant score if she was at the 67th percentile? I only have the standard deviation of the population and the mean. s = 27 . . . Percent Score, Percentile, Z-Score
# 458 :: 10/5/08	In 1992, the FAA conducted 86,991 pre-employment drug tests on job applicants who were to be engaged in safety and security-related jobs, and found th. . . Confidence Intervals, Normality Assumption
# 457 :: 10/4/08	What is a simple but legitimate power analysis formula? I am trying to do qualitative research on African American HS boys in the Midwest. I am using . . .
# 456 :: 10/4/08	I am trying to find out if a difference between two response sets is significant. I asked 98 boys what modalities they thought were attractive to girl. . . 2-proportion test
# 455 :: 10/4/08	Assume scores are normally distributed with a mean of 10 and std dev of 2. Find the first quartile Q1, which is the score separating the bottom 25% fr. . . Quartile
# 454 :: 10/4/08	what concerns arise from using formulae to calculate standard scores. . .
# 453 :: 10/4/08	A central university has a student population of 60,000. The university is interested in determining what proportion of them is in favour of a new gra. . . Sample Size, Margin of Error
# 452 :: 10/3/08	why does a z score always have a mean of 0 and a standard deviation of 1?. . . Standard Normal Curve
# 451 :: 10/3/08	A sample of the math test scores of 35 fourth-graders has a mean of 82 with a standard deviation of 15. Find the 95% confidence interval of the mean. . . Confidence Intervals, Confidence Level
# 450 :: 10/3/08	A researcher is interested in estimating the average salary of fire fighters in a large city. He wants to be 95% confident that his estimate is correc. . . Margin of Error, Sample Size
# 447 :: 10/2/08	If he correlaion between X and Y is equal to -1.0, what do we know about the prediction of Y by X? (a)It's negative (b) It's postive (c)It's perfect (. . .
# 446 :: 10/2/08	When using two predictor variables, these variables should be (a)Correlated (b)Related (c)Independent (d) Dependent. . .
# 445 :: 10/2/08	What must be used to examine an outcome that is predicted from two independent variables? (a)Multivariate regression (b)Multiple regression (c)Simple . . .
# 444 :: 10/2/08	What mut be done to categorical variables in order to use them in a regression analysis? (a)Nothing (b)Dummy coding (c)Problem coding (d)Categorical c. . .
# 443 :: 10/2/08	A postive trend line is associated with what type of slope? (a)Negative slope (b)Direct slope (c)Postive slope (d)Nondirectional slope. . .
# 442 :: 10/2/08	Using the regression Formula with slope=.704 and intercept=.719, what would the predicted college GPA be for a student whose current high school GPA=3. . .
# 441 :: 10/2/08	Which of the following Excel Function calulated the point at the regression line crosses the y-axis (a)SLOPE (b)CORREL (c)INTERCEPT (d)PEASON. . .
# 440 :: 10/2/08	How would you represent score of Y based on a known value of X? (a)Y (b)y-intercept (c)Y'(d)Y=Xa. . .
# 439 :: 10/2/08	I have a jar containing 100,000 marbles. There are 6 colors of marbles in the jar and they are present at frequencies of 2%, 2%, 4%, 10%, 57%, 25%. . . .
# 438 :: 10/2/08	How do i compute for the standard score (z-score)of the following data? How will the graph look like? 53 53 50 45 45 43 42 42 41 40 39 39 . . .
# 437 :: 10/1/08	how can i interpret standard or z scores?. . .
# 436 :: 10/1/08	when is ecological correlation appropriate? When is it not useful?. . . Ecological correlation
# 435 :: 10/1/08	Parametric and Nonparametric Data Identification Assignment Label each of the following situations “P” if it is an example of parametric data or “NP”. . . Non-Parametric, Parametric
# 433 :: 10/1/08	My data set is non-normal (cycle time). Can I convert the data into "Good and Bad" based on a specification and then find a Z value to estimate my sig. . . Cycle Time, Non-Normal Data, Log Transformation
# 432 :: 9/30/08	Assume that the population of heights of male college students is approximately normally distributed with mean m of 68 inches and standard deviation s. . . TDIST, t-score
# 430 :: 9/29/08	Individual scores of a placement examination are normally distributed with a mean of 84.2 and a standard deviation of 12.8. If the score of an indi. . .
# 429 :: 9/29/08	A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the coin biased toward heads? Show your decision rule. . . Normal Approximation to Binomial , 1-Proportion Test
# 428 :: 9/29/08	Each student in an experiment was told to look at 100 cars and count the number of people wearing the seat belts. The mean score for the class was fou. . . Z-Score
# 427 :: 9/29/08	Set up a model to test whether there are differences in mean ... DATA SET E Ages and Weights of 31 Randomly Chosen U.S. Nickels (n = 31 nickels) Nicke. . .
# 426 :: 9/29/08	can individual scores of a 542 student be converted into percentage and fed into spss for anova and tukey test. . . Percent Score, ANOVA
# 425 :: 9/29/08	A real estate agent has 2 tours. The first tour through N1and has 10 homes for sale, whereas the second tour through N2and has 5 homes for sale. The r. . .
# 424 :: 9/29/08	A recent article in a computer magazine suggested that the mean time to fully learn a new software program is 40 hours. A sample of 100 first-time use. . . 1-sample t-test, Alternative Hypothesis , Null Hypothesis , test statistic, p-value
# 423 :: 9/28/08	the lengths of human pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. What is the probability that a . . . Z-Score
# 422 :: 9/28/08	A newspaper finds that the mean number of typographical errors per page is five. Find the probability that: 1. Exactly five typographical errors wi. . .
# 421 :: 9/28/08	A surgical technique is performed on eight patients. You are told that there is an 80% chance of success. Construct a binomial distribution. Find. . .
# 420 :: 9/28/08	In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1050 kWh and a stan. . . Z-Score
# 419 :: 9/28/08	Suppose two events are independent. One event has probability of 0.25, while the other has probability of 0.59.. . . Multiplication Rule
# 418 :: 9/27/08	Dear Stats Person, Here is my question. If a person were to guess a number from 1-10, the chance of guessing a 4 would be 0.1. If 5 people were a. . . BINOMDIST, Binomial Probability, Binomial pmf
# 417 :: 9/27/08	Could you detail the value of using standard scores (Z scores) to compare relative performance of individual test scores.. . . Z-Score
# 416 :: 9/27/08	Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a second group do not. After 6 months, both groups . . . 2-sample t-test, Hypothesis Test
# 415 :: 9/27/08	how do i find the lower 25% and upper 75% and the interquartile range. . . Interquartile Range
# 414 :: 9/27/08	If you have 100 respondents identifying their gender, what would be the expected frequency for each category? a)25 b)50 c)75)d)100. . .
# 413 :: 9/27/08	In order to meet the sample assumption associated with parametrics statistics, how many subjects do you need? a)20 b)30 c)50 d)100. . .
# 412 :: 9/27/08	If you have 30 espondents identifying their political preference(i.e.,Democrat, Republican, Independent),what would be the expected frequency for each. . .
# 411 :: 9/24/08	Do you have any hints how I can figure out critical values at the significance level? Can you figure this out in excel or megastat? Is there a equat. . . NORMSINV, TINV
# 410 :: 9/24/08	You take a random sample of pizzas sold during a one hour period over the next week. Group 1 and Group 2 The results are shown in the table to the a. . . 2-sample t-test
# 409 :: 9/24/08	What is the height of a man with the z score of -1.7?. . . Z-Score
# 408 :: 9/23/08	Use Excel, or MINITAB to fit the regression model, including residuals and standardized residuals: DATA SET E Ages and Weights of 31 Randomly Chose. . . Minitab, Regression Analysis, Residuals
# 405 :: 9/22/08	Marge and Joe have five daughters. They decide to have another baby because they are sure the next one will be a boy (after all, what are the odds of . . . BINOMDIST, Multiplication Rule, Gambler's Fallacy, Probability Mass Function
# 404 :: 9/22/08	How do you calculate a standard deviation when your data is so large you can not enter it into the calculator. (I have 50 pcs of data). . .
# 403 :: 9/22/08	Based on information obtained from a sample of 54, a 98% confidence interval for the average profit level of regional banks is given by 67.4 million t. . . Standard Deviation, Margin of Error, Critical Value, Confidence Intervals, Confidence Level
# 402 :: 9/21/08	How can I compute a one-sided 97.5% confidence interval using SPSS for this ? IN a cohort of 121 eyes treated with drug A, 3 eyes experience a drug . . . SPSS, Confidence Intervals, 1-sided Interval
# 401 :: 9/20/08	A woman wrote to DearAbby and claimed that she gave birth 308 days after a visit from her husband, who is in the Navy. Lengths of pregnancies have a . . . Z-Score, Unusual Event
# 400 :: 9/20/08	What is the standard general score conversion formula? Is this the same as a z-score formula? Which leads me to ask How do you convert from one standa. . . Standard Score
# 399 :: 9/20/08	When you calculate CIs for time on task, I notice that you use the critical value from the t-distribution (TINV(0.05, degrees_of_freedom)). But when y. . . exact interval, Binomial Probability, TINV, Adjusted Wald, Wald Interval, Normal Approximation, Small Sample
# 398 :: 9/19/08	What is the formula for the exclusive range? What is the formula for the inclusive range?. . .
# 397 :: 9/19/08	mean score 100,standard deviation 20, z score-5 , what is the raw score?. . . Z-Score, Raw Score from Z-score
# 396 :: 9/19/08	what is the bottom of 20% of SAT. . .
# 395 :: 9/19/08	What is the Variance, Standard Deviation and Range of the following set of scores? 20,24,26,22,18,16,18 and then 10,15,12,18,19,16,12. . .
# 391 :: 9/18/08	An engineer in an automotive factory wishes to know what the tire pressure is on all cars leaving the factory. She measures the tire pressure on a sa. . . Standard Error of the Mean, t-statistic, Confidence Intervals, Critical Value
# 390 :: 9/18/08	How do you find the normal distribution when the mean is 50 witha standard deviation between scores of 32 and 47?. . . Area between, Z-Score
# 389 :: 9/18/08	How do you dertermine a z-score for continuous data?. . . Z-Score
# 388 :: 9/17/08	In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made. . . 2-proportion test, Binomial Probability, Normal Approximation
# 386 :: 9/17/08	I am calculating the effectiveness of an educational intervention using a pretest-posttest design. I plan to run an ANCOVA on the scores with the pret. . . Covariate, ANCOVA, ANOVA
# 385 :: 9/16/08	Given that the traveling distance for a population of college students is normally distributed with the mean of 10 kilometers and standard deviation e. . . Z-Score
# 384 :: 9/16/08	Test at the 5% level of significance whether the true mean time it takes for luggage to reach the travelers is less than 17 minutes. Determine the nul. . .
# 383 :: 9/15/08	Briefly describe the concept of a confidence interval and provide an example.. . . Confidence Intervals
# 381 :: 9/13/08	If I know the T-score for those who made an A on a test is 60, the z-score for those that made a B is .5, the number of students total is 200, how can. . . Z-Score
# 380 :: 9/11/08	What is the relationship between the sign of the correlation coefficient and the sign of the slope of the regression line?. . . Correlation, Regression Line
# 379 :: 9/11/08	1 a. with a mean of 300 and a standard deviation of 80, how high a score do you need to be in the top 30%? 1 b. What is the interquartile range for. . . Interquartile Range, Z-Score
# 378 :: 9/10/08	We have administered an anxiety test to all members of the class. The mean anxiety score is 71 and the standard deviation is 9. (higher score=higher a. . . Z-Score
# 377 :: 9/10/08	A sample of households that subscribe to the United Bell Phone Company revealed the following numbers of calls received by each household last week. D. . . mean, Median, Standard Deviation
# 376 :: 9/10/08	What statistical tests can I perform to compare two groups asked the same question, when the question has a yes/no answer and the sample groups are di. . . 2-proportion test
# 375 :: 9/9/08	why are histograms more appropate than bar graphs. . .
# 374 :: 9/9/08	A sample of size n = 14 is selected from a normal population to construct a 95% confidence interval estimate for a population mean. The interval was c. . .
# 372 :: 9/8/08	Can you please direct me to a site that would have an illustration of the normal curve that also includes cumulative percentiles, Z-score equivalents,. . . SAT Scores, Normal Curve
# 371 :: 9/8/08	Can you give me a formula to calculate sample size?. . . Sample Size, Margin of Error
# 370 :: 9/6/08	The accounting department at Weston reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours... Determin. . . Area between, Z-Score
# 369 :: 9/5/08	A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on very accurate scale. The results in grams were 3.087 3.. . . Margin of Error, Sample Size, Confidence Intervals
# 368 :: 9/5/08	in a random sample of 200 person of a town 120 are found to the tea drinker.In a random sample of 500 person of another town 240 are found to be tea d. . . Normal Approximation, 2-proportion test, Binomial Probability
# 367 :: 9/5/08	find the area under standard normal curve which lies (a) to the right of Z=1.76,(b)to the left of Z=.94,(c)to the right of Z=-.65,(d)b/w Z=.34 & Z=.62. . . Area between, Z-Score
# 366 :: 9/4/08	If I have 3 tables in the classroom with 16 girls and 8 boys in the class, what are the chances of 8 girls sitting at one table when seats are assigne. . .
# 364 :: 9/4/08	A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area . . . Margin of Error, Confidence Intervals, Sample Size
# 362 :: 9/1/08	Popcorn kernels take between 100 and 200 seconds to pop. What sample size (number of kernels) would be needed to estimate the true mean seconds to pop. . . Small Sample, Sample Size, Margin of Error, Confidence Intervals
# 361 :: 8/30/08	If I have a formula that predicts the winners of football games and it picked 600 out of 20000 games with 70% of the 600 being winners how can I estim. . .
# 360 :: 8/27/08	What does a negative z-score represent? eg. -0.381. . .
# 359 :: 8/27/08	You have a normal distribution and your subject has a z score = 0. What percentage of the group will be below your subject?. . .
# 358 :: 8/25/08	In the same set of data,can two or more elements have the same z score.. . . Z-Score
# 357 :: 8/25/08	Biting an unpopped kernel of popcorn hurts! As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them. . . Confidence Intervals, Normal Approximation to Binomial , Proportion
# 356 :: 8/24/08	The mean weight of 500 students is 151 lbs and the standard deviation is 15 lbs. Assuming the weights are normally distributed, find out how many stu. . . Area between, Z-Score
# 355 :: 8/20/08	If Range = (6 * Standard Deviation), can it be concluded that Data is normal. . . Nomal Distribution, Probability Plot
# 354 :: 8/20/08	A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.0. . . t-statistic
# 353 :: 8/19/08	A surgical technique is performed on eight patients. You are told that there is an 80% chance of success. a) Construct a binomial distribution. . . . BINOMDIST, Binomial Probability
# 351 :: 8/17/08	As an experiment, a self-confessed connoisseur of cheap popcorn carefully counted 773 kernels and put them in a popper. After popping, the unpopped ke. . . Confidence Intervals
# 350 :: 8/16/08	A robot, when working properly, produces 5% or less defective items. whenever the robot produces more than 5% defective items, i needs repair. A rando. . . Continuity Correction, Normal Approximation, binomial, 1-Sample Proportion Test
# 349 :: 8/15/08	A bank has determined that the monthly balances of savings accounts of its customers are normaly distributed with an average balance of $1200 and stan. . . Z-Score
# 348 :: 8/15/08	A random variable X is normal distributed with a mean of 250 and standard deviation of 50. Given that X = 175, what is its corresponding z-score? Rou. . . Z-Score
# 347 :: 8/14/08	Why is population shape of concern when estimating a mean? What does sample size hav