This is the final Renew or Cancel Index for the 2008-9 Broadcast TV Season (September 08 – May 09). The Index will return again to predict the fate of your favorite broadcast scripted shows in September, 2009.

The results, as they say, are in. The end of the 2008-9 broadcast TV season has left its typical trail of canceled shows, but also some surprises in the shows that were renewed for next season. Along with the final numbers for the season, I’ll propose some caveats that I’ll apply to my predictions next season.

For the 2007-8 season, the Renew/Cancel Index line fell quite dramatically at 0.92.  The future of a show was nearly directly related to its adults 18-49 average viewers divided by its networks 18-49 average viewers. If a show had better than 92% of its network’s average 18-49 viewership (0.92 in our index) it was pretty safe, below that level it was in danger.

For this season (2008-9) the results were far less clear. Many shows that were renewed fell far below an Index of 0.92, The New Adventures of Old Christine (a Wednesday show) was renewed with an Index of 0.67. Dollhouse (on Friday) was renewed with an Index of 0.56.  Likewise, some shows with Indexes well above last year’s line were canceled: My Name is Earl (1.05), Reaper (1.14), Worst Week (1.00). The strategy of culling your low performing shows to try and raise your ratings average results took a back seat to other factors this season.

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See the latest week’s Renew/Cancel Index here, including the latest predictions for which shows will be cancelled.

Last season I tried a variety of methods to predict which new shows were doing well and which were doing poorly. All of them suffered from a scaling problem. A massive hit for the pathetic CW could still be at the bottom of the list for another network. It was hard to analytically predict the likelihood of renewal or cancellation. But at the end of last season I decided to compare a show’s 18-49 viewership to its own network’s 18-49 average and the results were quite consistent in predicting renewal or cancellation (in this case after the fact).

For this upcoming season, I’ll use this method to publish a Renew/Cancel Index that I’ll be using to predict the future of shows across the broadcast networks.

To get these tables using last seasons results through early May I simply divided a show’s season to date average adults 18-49 viewership by its network’s STD adults 18-49 average viewership.* I’ve separated the scripted and unscripted shows into two lists. As it turns out, the predictive ability of the method for scripted shows is much better than it is for unscripted shows.

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