Summary
Contents
Subject index
KEY FEATURES: Examples for each statistical expression help readers understand complex formulas A chapter on how to use the literature for power analysis walks readers through the process of making good assumptions A chapter on how to write about power analysis offers 7 key points on what needs to be included in a power analysis
Using Covariates When Testing the Difference in Sample Group Means for Balanced Designs
Using Covariates When Testing the Difference in Sample Group Means for Balanced Designs
In this chapter, I expand the analysis of group differences in means to include the use of covariates. The effect that a covariate has on power can be both beneficial and harmful, depending on the correlation between the treatment indicator variable and the covariate. The parameters for power are outlined for both the case in which there is correlation between treatment indicator and the covariate, and the case in which the treatment indicator and the covariate are uncorrelated due to randomization of the treatment condition. For brevity, we consider only balanced designs.
While this chapter goes ...
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