Since the 1950s, Nielsen Media Research has been measuring television viewership and ratings. Nielsen ratings include demographical information, including number of viewers and the share of viewers.
TV networks heavily rely on Nielsen data, and the future of many shows depends on the ratings they earn.
What are Nielsen ratings?
So what are these Nielsen ratings and how do they work? Ratings are calculated using statistical sampling. They use a sample audience to gain information about viewing habits. They then use that data to estimate how many people in the total population watched the same show.
How do Nielsen ratings work?
Since the 1950s, TV has changed tremendously. The same rating system is still in place, just altered a bit to account for TiVo and other DVR systems.
The all-time highest rated program is I Love Lucy from 1952-1953, with a 67.3 rating. In comparison, the highest rated program of 2011-2012 was NBC Sunday Night Football with a 12.9 rating.
Nielsen gets its data by giving around 5,000 households Nielsen boxes that record information about the shows watched in these households. This is an extremely small sample, as nearly 97% of American households have televisions.
How are Nielsen families chosen?
Nielsen families, as participants are called, are chosen randomly. Nielsen has stated that the only way to get an accurate sample is to choose households randomly to represent the community as a whole. Every household has the same chance to be selected to participate.
College students represent an important segment of the TV-watching demographic, and are selected often to participate. In these cases, roommates participate as a family.
Nielsen sends equipment and TV diaries to its participants, and pays them for their help.
How do ratings affect shows?
Network shows on CBS, ABC, NBC and Fox aren’t likely to last long if they cannot pull high ratings and viewership numbers. Even shows that are scoring well could be canceled because other shows on the network are doing better.
Sweeps week is really actually a month of intense Nielsen ratings to determine advertising rates. The better ratings a show earns during the period, the more the network can charge for commercials.
February, May, July and November are the standard sweeps periods. New households are mailed paper diaries during each week of sweeps to get fresh information throughout the month.
During sweeps week, shows often stray from plot lines and pull out the craziest episodes to get more viewers to tune in.
Adjusting Nielsen ratings for DVRs
The Nielsen system is fairly dated, as ratings are still calculated as they were in the 1950s. Recently, Nielsen began accounting for some DVR viewing as time-shifting of shows became more popular.
Networks continue to rely heavily on ratings and viewer numbers from Nielsen, and that doesn’t seem to be changing any time soon.