## Statistics Tutorials

Introduction to Confidence IntervalsUnderstand the margin of error, the confidence level and how confidence intervals describe the variability of a samples.

The Standard DeviationVariability is a fundamental concept in statistics. This tutorial covers the standard deviation and why measuring variability is so important.

Fundamentals of Statistics 1: Basic ConceptsIf you know nothing about statistics, this is the place to start. The tutorial covers basic concepts such as the mean, standard deviation, populations and sample statistics.

Fundamentals of Statistics 2: The Normal DistributionThis tutorial continues where Fundamentals I left off. It covers the normal distribution in detail including how to find the probabilities of events using the normal curve.

Fundamentals of Statistics 3: SamplingSampling distributions, the standard error and applying the normal distribution to make predictions will become the foundation for almost everything you do in statistics.

Comparing Two Means: 2 Sample t-testIs there a statistically significant difference between two groups? The 2-sample t-test is the most popular statistical test and this tutorial shows you in vivid animation how it works and how you can use it to compare two means.

## Calculators

2 Sample t-testCompares the means of two data-sets using the t-distribution.

1 Sample t-testCompares the means of one data-set against a test mean using the t-distribution.

Percentiles from the t-DistributionCalculates the percent of area under the student t distribution given a t-score and degrees of freedom.

Inverse t-DistributionCalculates the critical value from the student t distribution given a proportion of area and degrees of freedom.

Standard DeviationComputes the sample standard deviation and population standard deviation from a dataset.