Do It Yourself!: Comparing t and z

This applet shows the comparison between the standard normal (z) distribution (red) and Student's t distribution (blue). Move the slider to change the degrees of freedom for Student's t distribution and notice how much it overlaps with the normal distribution.

Change df with the slider to compare the two-tailed critical values for t and z when alpha = .05. You can find other critical values by changing the tail area in the box marked "prob".

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The applet(s) on this page is from Seeing Statistics,™ an online, interactive statistics textbook. Seeing Statistics is a registered service mark used herein under license. The applet(s) on this page was designed to be used exclusively with Introduction to Probability and Statistics, Eleventh Edition, by Mendenhall, Beaver, & Beaver. (c) 2003, Duxbury Thomson Learning. The applet(s) on this page may not be copied, duplicated, or reproduced for any reason.