There was an interesting article last week on Variety talking about how Netflix crunched the numbers and figured out which episodes of various television series were the ones that got people hooked. This is something the company would be very interested in since their business model is based on binge watching and trying to find what gets viewers hooked would be very helpful. The problem is, I don't know if they actually found anything from this research.
Now they don't breakdown their criteria, but it seems pretty straight forward as you look at the viewers and the natural attrition that takes place and you see at what episode the number of viewers who no longer move forward with the series drops below your expected threshold… when you find the episode that retains the most viewers that complete the series then you have the hook episode.
Judging by some of the results, it appears to be all over the board to what episodes they are.
For Arrow it was Episode 8 while Daredevil got folks hooked on episode 5. It only took 2 episodes of Breaking Bad but 4 for Better Call Saul. Dexter, House of Cards, Marco Polo and Sense 8 all got people with episode 3.
I'm not sure how this data can be used to improve future series or give them a better idea of which series to pick up as the series are so diverse it would be hard to find a common thread in the hook episodes… but there is one thing to take away from this: not one of the series they looked at hooked people with the pilot episode.