Statistics

Interview question

seniorlevel
12 minsuggested time
2Data scientist, Data analyst

An airline flags the 10% of routes with the worst on-time performance (OTP) in Q1 and sends them a punctuality programme. In Q2 those routes improve from an average of 71% to 77% OTP. The operations VP wants to roll the programme out network-wide and quotes "+6 points". The other routes did not change on average. What would you say before this goes to the board?

Tests: Recognising regression to the mean and selection on the outcome; separating a programme effect from the statistical expectation of improvement; designing a fair comparison.

day 5