DrParrett Is a Sports Psychologist for a Large Southern University

Dr.Parrett is a sports psychologist for a large Southern university.The provost and chancellor have asked him to examine the relationship between athletic performance and academic stress at the university.For example,is it the case that the most talented athletes experience the greatest concern over their grades? The provost and chancellor have made it clear to Dr.Parrett that they want a large amount of external validity in the study.He has valid and reliable measures of both athletic performance and academic stress.He knows that he does not have the time or the money to study the entire population of interest.

-What is the population of interest in Dr.Parrett's study? Will he be collecting a sample or conducting a census? Why does he need to be concerned with external validity/representativeness?