Variables Affecting Power

This applet allows you to vary the three major variables affecting power. You can alter the difference between the means, the standard deviation of the populations, and the sample sizes. You can then see how these affect subsequent power.

The applet is shown below

Use the scrollbars to change the standard deviation (left), number of observations (right), or mean for group 2 (bottom). Observe the resulting statistical power. Click on graph to reset original values.

Set the means at 4.0 and 6.0, the standard deviations at 1.7, and put 10 rats in each group. How does this compare to the results we found in the study of hoarding behavior?
How many rats would we need under those conditions to have power = 0.95?

Comments to: Gary.McClelland@Colorado.edu

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