Question 355:

Asked on August 20, 2008

Tags: Nomal Distribution , Probability Plot

1

Answer:

No answer provided yet.Not conclusively, but there is some evidence that the data are symmetrical and spread similar to a normal distribution, where 99% of values fall within 3 standard deviations +/- the mean. The data could still have lumps in the middle marking a departure from normality, as such this is no guarantee of a normal distribution. You should plot your data, ideally using a normal probability plot (Q-Q plot) to view how close to normal the data are. With no other information though, this does provide some evidence for normality. Also keep in mind that most parametric tes (t-tests, ANOVA etc) can handle some departures from normality, meaning as long as the data isn't very non-normal, you're usually ok.