By asking this broad question Kevin is testing to see if Michael can communicate, without prompts, those 4 specific attributes McKinsey seeks in a PEI.
By continuing this theme of questioning, Kevin is signalling that the initial answer probably did not provide the information he was seeking.
Kevin is focusing the discussion on neuroscience specifically around the data analyses part. Michael needs to demonstrate he can explain the logic and insights in his analyses.
Kevin is continuing the theme of problem solving, which indicates Michael’s previous answer was probably insufficient. Michael struggles to explain the problem and solution.