The preliminary TV ratings (also called the “fast affiliate ratings”) measure whatever aired on each local affiliate station during a given time period.
For shows that air in the same time period in every time zone, the preliminary ratings are usually the same as the final ratings.
However, a number of common scenarios can cause adjustments to the preliminary ratings in the final ratings.
- Live Events – When programs air live across the country (like sports) the viewing that occurs in the Pacific and Mountain time zones is “missed” by the preliminary ratings. That “missed” viewing is added into the program’s ratings in the final ratings adjustments. Also, whatever viewing for other programs that aired in primetime in the Pacific & Mountain time zones “instead of” the live event, that was originally included in the preliminary ratings is removed in the final ratings.
- Local pre-emptions – When a different program airs locally than what the network scheduled nationally (typically local sports), that viewing is included in the national program’s preliminary ratings and often “inflates” them and is removed in the finals ratings adjustments. There are very occasionally national pre-emptions (for breaking news). That viewing (included in the preliminary ratings), is subtracted in the final ratings.
- Overruns – Networks often add a minute (or two) to high rated shows in order to sell advertising at the higher rated show’s rate (ex. Modern Family often runs from 9:00-9:31). The preliminary ratings for Modern Family measures only the 9:00-9;30 time period. The extra minute of viewing is added in the final ratings adjustments. Likewise, the viewing is removed from the preliminary ratings of the show that runs from 9:30-10 in the final ratings adjustments.
Preliminary “fast affiliate” ratings are released at about 11am Eastern time each day for the previous night.
Final ratings are released at about 4pm Eastern each day for the previous night, except Friday final ratings are released at 4pm Monday, and Sunday final ratings at 10am Tuesday.
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