This is a noble project but I'm concerned that it may not be a methodologically valid blind study.
Specifically, in order to be a blind study of the relationship between the screening exam and technical interview performance, the technical interviewers should not know the results of the screening exam before they make their decision. While they do not state this clearly, it seems possible that since the same 2 people were conducting all steps themselves, that they were not properly blinded.
Thus we cannot rule out confirmation bias in the interviewers themselves, i.e. that they were impressed by good performance on the programming quiz, not that it was an independent predictor of good performance in the technical interview.
Now, maybe one person did the screening and the other did the technical interview with no information sharing in every case, but this would need to be clarified.
Specifically, in order to be a blind study of the relationship between the screening exam and technical interview performance, the technical interviewers should not know the results of the screening exam before they make their decision. While they do not state this clearly, it seems possible that since the same 2 people were conducting all steps themselves, that they were not properly blinded.
Thus we cannot rule out confirmation bias in the interviewers themselves, i.e. that they were impressed by good performance on the programming quiz, not that it was an independent predictor of good performance in the technical interview.
Now, maybe one person did the screening and the other did the technical interview with no information sharing in every case, but this would need to be clarified.