Which CBS TV shows will be cancelled or renewed for the 2011-12 season? With the greatest number of series on the air, CBS continues to be the most-watched network. Other than now-cancelled Medium, they really don’t have any big problems on the schedule.

The Sunday night line-up — 60 Minutes, The Amazing Race, Undercover Boss and CSI: Miami — have seen some off nights but they’ve also endured annoying overruns caused by football games. Of any, CSI: Miami is in the most danger. It’s been on the air a long time and is likely not cheap.

Blue Bloods and CSI: NY are definitely on the fence as they’re both averaging a 1.8 — about what Numb3rs and Medium were averaging last year. In that case, one was renewed and the other was cancelled so it’s hard to say. It seems likely that only one will survive and CSI: NY is older and probably more expensive. The Defenders is a lackluster performer so it’s reasonable to think, unless the ratings improve, that CBS execs will cancel it and opt to try something else. The Good Wife could certainly be in danger as well.

Below is a list of the regular CBS TV shows and their 2010-11 season average ratings to date. It only incorporates the ratings for original episodes that have aired this season (no repeats). The data is sorted by the 18-49 demographic averages, the group that advertisers will pay the most to reach and, therefore, how the network measures success.

The closer a show is to the bottom of the list, the closer it is to being cancelled (if it hasn’t been cancelled already like Medium). If it’s closer to the top of the list, it’s more likely to be renewed. Shows that are in the middle (“on the bubble”) can be a little tougher to call. Their future typically comes down to other factors like overall costs, contracts, who produces the show, and what new shows are on the horizon.

The list has been separated into two sections. Of the two, scripted programming is the most expensive. News and reality TV shows are less expensive to produce but the networks can’t program just news/reality (though they might like to since they are less of a financial risk).

It should be noted that Friday and Saturday nights are the least watched evenings of television so ratings for shows on those nights are lower. The networks understand this and take it into account. However, regardless of when a show is aired, its production costs remain the same. Ultimately, it must still be profitable enough for the network to keep ordering more episodes.

Raw data: © The Nielsen Company via Media Week. * Nielsen doesn’t release the final Friday and Saturday night ratings until a few days later. Numbers with an “*” may change slightly once the final numbers are released.

What do you think? Which shows do you think won’t survive to see a new season?

Image courtesy CBS.