The conclusion is misleading due to 2 wrong assumptions:
1. The population is heterogeneous: interviews test different skills. All interviews don't test the same set of skills, which is mandatory to compare interview scores because scores are aggregates of these skill tests. Different job opportunities means different skills to test, so it seems reasonable to assume that people evaluation vary for different job opportunities, and thus their scores vary for different interviews.
2. The observations are not statistically independent: past interviews may influence future interviews. People may get better at passing interviews or conducting interviews over time. This would impact their score. It would be good to study the evolution of individual scores over time.
While (1) should strongly limit the conclusions of the study, the complete analysis may simply be irrelevant because of (2) if the statistical independence of observations is not demonstrated. Sorry guys but this is Statistics 101 introductory course.
1. The population is heterogeneous: interviews test different skills. All interviews don't test the same set of skills, which is mandatory to compare interview scores because scores are aggregates of these skill tests. Different job opportunities means different skills to test, so it seems reasonable to assume that people evaluation vary for different job opportunities, and thus their scores vary for different interviews.
2. The observations are not statistically independent: past interviews may influence future interviews. People may get better at passing interviews or conducting interviews over time. This would impact their score. It would be good to study the evolution of individual scores over time.
While (1) should strongly limit the conclusions of the study, the complete analysis may simply be irrelevant because of (2) if the statistical independence of observations is not demonstrated. Sorry guys but this is Statistics 101 introductory course.