DrFletcher Is Interested in Understanding Whether Joining a Fraternity/sorority Causes

Essay

Dr.Fletcher is interested in understanding whether joining a fraternity/sorority causes people to become more concerned about their attractiveness and appearance.He recruits a group of 55 freshmen (25 males,30 females)who are planning to go through fraternity/sorority recruitment on his campus.After they join,he gives them a measure of attractiveness concern/appearance concern (the Body Concern Scale,where higher scores indicate higher body concerns).

-In addition to measuring the body concern of the participants who joined a fraternity/sorority immediately before and immediately after they join,Dr.Fletcher measures them for the three weeks before and the three weeks after.Based on the results below,explain whether Dr.Fletcher should be concerned about a testing threat to internal validity.