With the fact that Fox is crushing the competition in season to date ratings, there are often discussions on our site about Fox's average ratings advantage because it programs only 15 hours a week instead of the 22 hours that ABC, CBS and NBC program. No one seems to be talking about the advantage that CW gains by only programming 12 hours a week, and skipping the weakest night of the week (Saturday) entirely. I guess only success is questioned. Failure is ignored.
The conventional wisdom is that gives Fox two advantages: (1) Fewer people watch TV at 10pm, and (2) It gets increasingly hard to program primetime hours, and Fox needs put on only its "best" 15 hours, not a presumably "second string" additional 7 hours.
How does that conventional wisdom stack up to reality? Let's look at the numbers.
Weighted Average Viewership For Each Hour, Season To Date*
8pm vs 10pm
9pm vs 10pm
1. Fewer People Watch TV at 10pm.
Not true for NBC, it's their best hour. And CBS does better at 10pm than 8pm. Only ABC does universally worse at 10pm, and much worse than its 9pm hour.
It needs to be emphasized that the numbers above are season to date, times of the year effect time periods differently. Currently, the 8pm hour viewership is suffering disproportionately because of Daylight Savings Time. Trying to sort that out is beyond what I'm able to do with my existing data.
I'd say the idea that 10pm is more difficult to program solely because of the hour is true, but I'd call it a slight disadvantage, less than 10% for the hour, and averaged over the night maybe 3%.
*Methodology: The weighted average by hour was calculated by taking the average viewership of each show regularly beginning in the broadcast hour and weighting it by the total broadcast duration of the show season to date as of April 13, 2008. This method has a number of limitations. Shows that last more than an hour are completely counted in the hour in which they begin. That's the best we can do with the data we have available. If someone out there has actual hourly average data, we'd love to see it. Also, note that any show designated as a "special" does not show up in any aggregate network numbers. Networks have a very wide latitude in which shows they designate as "special".
** The Sunday 7-8pm hour, not an average of multiple days.
***A number of shows (2-7) for each network were noted as having "various" start times. Those were averaged together and shown for reference only. NBC's exceptional value is due to Sunday Night Football being designated as "various".
2. It Gets Increasingly Hard to Program Successful Shows
If that was the case, you'd expect to see that in a steep viewership curve from top to bottom for individual networks.
This chart shows the season to date viewership of each of the top 30 shows in the 4 networks for the current season. Shows with multiple airings per week [Dancing with the Stars, American Idol, Deal or No Deal] have each airing counted separately.
Based on these curves, I think that conventional wisdom is true.
It shows some interesting patterns. Programming shows with STD average viewership above 15 million viewers is very rare. CBS and NBC manage only one each. Fox manages only 3. ABC seems to do much better with 5, but that's counting 4 different timeslot airings of Dancing w/ the Stars, two of which are rare.
If you figure that the top 20 shows are the strength of each network, CBS shows the most "bench" power. Its #18 show, averages 10 million viewers. Conversely, Fox and ABC have the most "star" power, their averages are lifted by their top handful of shows. NBC has neither stars nor bench.
Confirming the conventional wisdom about Fox programming weakness, their dropoff from the top shows is more pronounced than the other 3 networks and their "bench" shows average consistently less than the other networks through nearly the entire range.
If you assume that if Fox had to add another 7 hours of programming per week, and each of those hours garnered only 5.5 million viewers, here's the effect to their overall average.
Current Fox STD viewership average: 11 million x 15 hours/week = 165m viewer-hours.
Add 7 hours x 5.5 million viewers = 38.5m viewer-hours
Totaling 203.5m viewer hours for 22 hours, an average of 9.25m viewers.
So, it's reasonable to guess that Fox would suffer a penalty of about 15% if it had to program the additional 7 hours, dropping it behind CBS into second place for viewers.
However, Fox's lead in adults 18-49 is so large that I believe they'd maintain their #1 position. If I get the inclination, I rerun the same analysis for adults 18-49, but don't hold your breath.
Nielsen TV Ratings Data: ©2008 Nielsen Media Research, Inc. All Rights Reserved.