I would applaud the author on trying to take a data-driven approach to discover the best hiring signals, but I must offer one major critique of the approach: These data are ultimately not too meaningful unless you correlate actual job performance with interview performance. By the author's own admission, interviews are often faulty. By correlating final-round interview performance with early-round interview performance, you are really only predicting how candidates will perform in the final-round interview, which is not necessarily a good predictor of long-term job performance.