Retention Is the Better Part of Valour

I'm still surprised when I read analyses of Nielsen ratings. I still see statements like "Retention for 'Studio 60' out of 'Heroes' was just 77 percent in the overnights, 72 percent in total viewers and 66 percent among adults 18-49."

It doesn't really mean that 72% of the viewers who watched 'Heroes' also stuck around to watch 'Studio 60.' It simply means the audience for 'Studio 60' was 72% the size of the audience for 'Heroes.'

Historically, that statement made sense. Nielsen had a tough enough job just estimating the number of viewers for a given show. Forget about trying to estimate the number of viewers who watched both shows.

With all data that's available now, why don't we see real retention numbers? Why doesn't Nielsen report viewership like 6.9(5.2)? That data would tell us that 6.9 million people watched the show and 5.2 million of those people also watched the show before it. I would love to know how many people actively sought 'Studio 60' at 10PM instead of maybe just leaving the TV on after 'Heroes.'

I'm guessing Nielsen already has this data but only provides it to its paying customers. If Nielsen does have this data, I hope that we can choose better words to more accurately report ratings.