Using a pretest score as a covariate in repeated measures in SPSS GLM

Troubleshooting

Problem

In an experimental design with one or more treatment and control groups, a commonly used covariate consists of scores on some pretest, measured using the same scale as that for the dependent variable (i.e., a posttest). In such an ANCOVA model, the question posed is: "Is there a difference in the mean posttest scores after adjusting for pretest scores?" My question concerns extending this logic to repeated measures models. Can you use the pretest score as a covariate to adjust for baseline values in analyzing a series of posttests and/or follow-up tests in repeated measures ANCOVA? If you do this, are you answering the question "Is there a difference in the posttest repeated measures after adjusting for the pretest scores?"

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Historical Number

19705

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Document Information

Modified date:
16 April 2020

UID

swg21476717

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