If there are ratings drops for Thursday night's broadcast primetime ratings (to be posted between 11:30-Noon Eastern), you can be certain that Fan Excuse Bingo players will be covering the "But It Was Valentine's Day!" square like crazy in our comments and elsewhere.
Is there data to back that excuse up, or is it just fan desperation (and network PR spin) to claim that Valentine's Day depresses ratings?
The last two Valentine's Days that fell on weekdays saw 7% and 6% declines in overall primetime adults 18-49 viewing vs. the previous week. The last Thursday Valentine's Day (2008) saw a 4% decline. Ignore 2010 for comparison purposes, the week before Valentine's Day was Super Bowl Sunday.
Before we see the adults 18-49 PUT (people using television, you can think of it as combined total rating) for primetime last night, you can reasonably guess that Valentine's Day is likely to reduce overall adults 18-49 viewing in the mid single digit %'s.
Updated: Last Thursday (2/7/13) the adults 18-49 PUT in the primetime fast affiliate ratings was 36.3, Last night it was 34.3, a decline of 6%. That much you can blame on St. Valentine, any more than that is just Fan Excuse Bingo.
Update 2: For the Fan Excuse Bingo players grasping for that very last square, the hourly declines vs. last week were 7%, 6% and 4%.
Valentine's Day Usage Trending vs. Prior Week (2012-2008) Live + Same Day
Source: NTI, PUTs, Live+Same Day.