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1. Please download the Apple Runtime for Java available for FREE at (if you already have the Apple Applet Viewer, skip to step 5):


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3. Click on the MRJ Install icon to install the applet viewer.

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It will be worth your time, I promise!

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When the applet is loaded, go to the applets menu and select add applet to list.

Statistics: t-test

The t-test is employed when one wishes to determine if two samples have statistically different means. The t statistic is calculated as:

where the pooled variance, , is calculated as:

If t is less than the critical value, then the two samples have statistically different means. The critical value can be determined given the sample sizes, the level of significance chosen (typically a = 0.05), and a critical value table.

Statistics: t-test

Adjust the means, variances, and sample sizes to the right:

Increasing the difference between the means of the samples will increase the t value; decreasing the difference will decrease the t value. Increasing the variance will decrease the t value, whereas decreasing the variance will increase the t value. Changing the population sizes will affect both the t value and the critical value.