Examination for Professional Practice of Psychology (EPPP) Practice Test

Which of the following factors does not influence a predictor's incremental validity?

1. Criterion-related validity coefficient

2. Sample size

3. Selection ratio

4. Base rate

The correct answer is: Sample size

Incremental validity refers to the extent to which a new psychological measure or predictor contributes additional information about a criterion beyond the information already provided by existing measures. In this context, a factor that does not influence Incremental validity is the sample size. Sample size primarily affects the stability and reliability of the estimates of validity. While a larger sample size can provide more accurate and generalizable estimates of validity coefficients, it does not intrinsically enhance the predictive power of a specific predictor over and above what is already known. The actual incremental validity of a predictor is determined by how much additional variance in the criterion can be explained after accounting for other predictors, not simply by the size of the sample being used to evaluate it. In contrast, the criterion-related validity coefficient reflects how well the predictor correlates with the outcome measure, suggesting that if the coefficient is high, the predictor could be a strong candidate for having high incremental validity. The selection ratio, which is the ratio of the number of individuals selected to the total number of individuals assessed, affects how well a selection measure performs in different contexts, thus influencing its incremental validity. Lastly, the base rate, or the prevalence of the criterion in the population, can also influence how a predictor performs in real-world settings and thus contributes