Examination for Professional Practice of Psychology (EPPP) Practice Test

In a study comparing strategies for teaching statistics, what statistical technique should the researcher use after realizing group assignment errors?

1. Analysis of covariance (ANCOVA)

2. Randomized block ANOVA

3. Multivariate analysis of variance (MANOVA)

4. Split-plot ANOVA

The correct answer is: Analysis of covariance (ANCOVA)

In the context of a study comparing strategies for teaching statistics, the use of Analysis of Covariance (ANCOVA) becomes relevant particularly when there is a need to control for variability due to group assignment errors. ANCOVA allows researchers to adjust the means of the dependent variable based on one or more covariates, which helps to account for any pre-existing differences among the groups that might have arisen from these errors. By including covariates that may influence the dependent variable, ANCOVA provides a more accurate estimation of the treatment effects by reducing error variance and thus increases the statistical power of the tests. This is particularly important when the random assignment has not been successfully maintained, ensuring that the conclusions drawn regarding the effectiveness of the teaching strategies are valid. While other statistical techniques like Multivariate Analysis of Variance (MANOVA) or Split-plot ANOVA might be applicable in different scenarios, they do not serve the specific purpose of controlling for group assignment errors as effectively as ANCOVA does. Randomized block ANOVA could be used when there are specific blocking variables, but it would not address the nuances of adjusting for group assignment errors in the same manner that ANCOVA would.