Power of Within-Subjects Designs Demo

Questions to be answered before the simulation are not yet implemented in this test version.


Begin by answering the questions, even if you have to guess. The first time you answer the questions you will not be told whether you are correct or not.


Once you have answered all the questions, answer them again using the simulation to help you. This time you will get feedback about each individual answer.


General Instructions


This applet demonstrates the effect of the correleation between measures in a one-way within-subjects ANOVA with two levels. This test is equivalent to a correlated t test. The default values for this demonstration are for an experiment with 10 subjects each measured under two conditions. The population difference for the two conditions is 1.85 and the variance in each of the conditions is 4.0. The graph shows the power of the test as a function of the population correlation between the two scores for the 0.10, 0.05, and 0.01 significance levels. The power of an independent-groups t test (which assumes the correlation is 0) is shown by the x’s.


Step By Step Instructions


Experiment with different combinations of the parameters. Is the correlation an important factor in power?


Summary


Correlation is a critical factor in the power of within-subjects designs.