As it relates to television series, the hook index is the average number of episodes one must watch before they are committed to watching the rest of the series. For instance, Breaking Bad may have a hook index of 3. Meaning, you have to make it through episode three in order to really stay with the series (mostly because of the icky bathtub scene from episode 2.
Parks and Recreation has a hook index of 6. Because it was so similar to The Office, views drastically declined in the first season until the last episode (6) where "Despite the low rating, "Rock Show" received the best reviews of the season and convinced some critics that the series had finally found the right tone."
by RichardNavarrete June 4, 2019