For 50 years, Nielsen has provided audience estimates for network TV shows. For 37 of those years, the methodology remained the same: using a combination of electronic meters to measure household estimates and diaries kept by viewers to collect demographic information. In 1987, Nielsen introduced the peoplemeter, which collects data electronically.
Nielsen has also provided ratings for local TV stations for 46 years, using largely the same methodology. Here's a run down of the core NMR services:
- Nielsen Television Index, or NTI. Using peoplemeters, it provides household and demographic ratings for national broadcast network TV shows on a daily basis.
- Nielsen Station Index or NSI. This is the service that measures local TV ratings in all 210 Nielsen markets. Currently, 48 of the top markets are measured with a combination of meters (for household data) and diaries (for demographic data).
- Nielsen Home Video Index. Established in 1980, NHI measures cable networks and VCR recording from data collected through the peoplemeter nationally and set meters and diaries locally.
- Nielsen Syndication Service, or NSS, was started in 1985 to measure audiences for the syndication-program business. The data is collected from the peoplemeter and the local meters and diaries.
- Nielsen Hispanic Television Index, or NHTI, collects viewing data from a national sample of 800 Hispanic households, using peoplemeters. Nielsen also measures local viewing in Hispanic households in 16 markets for the Nielsen Hispanic Station Index.
- Nielsen Monitor-Plus is a service that tracks ad spending in 15 different media.
- N-Power is a software package that provides access to individual-viewing and household data.
- Nielsen NetRatings, formed in 1998, provides data about Internet usage.