A researcher studying depression in relation to five predictor variables decides to include five ...

ANS: A
As the number of variables under study grows, the needed sample size increases. Adding variables such as age, gender, ethnicity, and education to the analysis plan can increase the sample size by a factor of 5 to 10 if the selected variables are uncorrelated with the dependent variable. Setting beta lower, performing additional reliability and validity tests, and changing the design from correlational to descriptive will not solve the problem of the altered power of the study, due to addition of five variables. Only increasing the sample size will be a practical solution.