Every week we see press releases from ABC, NBC and CBS touting their late night ratings. In theirs, ABC's skilled PR team makes the comparison between Nightline's ratings (which runs from 11:30p-12a) and The Tonight Show and Late Show ratings (which each run from 11:30p-12:30a).
I always assumed that in the half hour they went head to head, that Nightline was getting beaten (perhaps badly) by the other two shows. As it turns out, the ratings in that half hour are a lot closer than I had thought.
Here is the average half hour ratings breakdown for last week (November 2-6):
11:30-midnight (Live+SD adults 18-49 ratings)
NBC Tonight Show: 1.0 rating
CBS Late Show: 1.0 rating
ABC Nightline: 1.0 rating
NBC Tonight Show: 0.9 rating
CBS Late Show: 0.8 rating
ABC Jimmy Kimmel: 0.6 rating
While it's only a single week, and it's fair to continue to note that the Nightline ratings PR is still advantaged by comparing a 30 minute show to 60 minute shows, the magnitude of the advantage isn't what I thought it was.
And to anticipate the question, we are not going to be getting regular half hourly late night ratings.