A Guide to Frequently Used Audience Measurement Terms
DEFINITION: The number of U.S. public television (PTV) stations carrying a program.
PROGRAM OR DAYPART: Carriage is reported for programs. It is usually reported for the entire country. However, it can be segmented by day of the week, time, geography, and portions of the population.
MORE ABOUT CARRIAGE: Carriage figures will grow as the queried length of time grows. This is especially true for standalone programs, limited series or non-prime time programming.
TRAC’s carriage is purchased from XPERI. Data are first reported for four weeks into the future and updated daily as time moves closer to date of broadcast.
FORMULA: The number of different stations airing a program across a specified time period. There are between 349 and 379 PTV analog stations depending on the definition of “station.”
EXAMPLE: Two hundred stations are carrying a program across a specified week. In a month, a carriage query shows the number of stations that carried the program increased to 226.
DEFINITION: The percentage of U.S. TV population that can receive a given PTV program during a specified date range
PROGRAM OR DAYPART? Coverage is reported for programs. It is usually reported for TV households in the entire country. However, it can be segmented by day of the week, time, geography, and portions of the population.
MORE ABOUT COVERAGE: Coverage figures grow as the queried length of time grows. This is especially true for stand-alone programs, limited series or non-prime time programming.
TRAC’s coverage is computed using the Nielsen-determined coverage percentage for each TV market which is updated once per year at the start of the new TV season. TRAC uses XPERI schedule data to find markets where selected programs are scheduled. This is first reported for four weeks into the future and is updated as the broadcast date grows closer.
To calculate coverage, each market is counted only once regardless of the number of times the program plays in the market. This means that if multiple stations or channels in a market carry a program, that market is still only counted once in the coverage figure. There are 210 Nielsen Designated Market Areas (DMAs. See Other Terms).
FORMULA: Based on Nielsen’s TV household figures, coverage percentages are computed for each market. Coverage percentages are summed for all markets where a program is broadcast during a specified time period.
EXAMPLE: WNET (New York) and PBS SoCal (Los Angeles) were the only stations that carried a hypothetical program in a specified week. Total coverage equals New York (7% of U.S households) plus Los Angeles (5% of the households). That means 12% of the households in the country had the opportunity to view this program.
DEFINITION: The percentage of different households that view a station for five minutes or more. (Also known as Circulation, Reach, Unduplicated Audience.)
PROGRAM OR DAYPART? Cumes are usually reported for a week, sign-on to sign-off. Cumes can be reported for shorter time periods such as prime time (8-11 pm Eastern Time Zone, 7-10 pm Central Time Zone) or for a single program.
MORE ABOUT CUMES: Cumes are sensitive to the length of the time period being measured. Usually, as the time period grows, so does the cume. Cumes from dayparts of different lengths should not be compared.
Like all audience estimates included in this booklet, cumes can be computed for households or for demographic groups (such as women over the age of 18).
Cumes and other audience estimates can be based on different geographical areas, such as metro cumes or DMA cumes (see Other Terms). Cumes are measures of the number of different homes or individuals that viewed. The larger the cume, the more homes or people have viewed a station.
FORMULA: Number of different homes or individuals that viewed a station for five or more minutes divided by the total number of homes or individuals in a market. The result is multiplied by 100 to express the cume as a percentage.
EXAMPLE: There were 500,000 homes that viewed WPBS in a market of 1,200,000 homes during a seven-day period. The cume is 500,000/1,200,000 or .4167. Multiply by 100 and round the results to 41.7. That means 42 percent of all the households in the market viewed WPBS during the week.
DEFINITION: GRPs are quarter-hour or half-hour ratings summed across a given program or daypart. GRPs are used instead of ratings to denote the amount of viewing attracted by a program or daypart. GRP is an acronym for Gross Rating Point. (GRPs are also known as Total Viewing or Viewing Tonnage).
PROGRAM OR DAYPART? GRPs are generally reported for a variety of dayparts or time periods (a day, week or month), although GRPs can also be computed for programs.
MORE ABOUT GRPs: GRPs are sensitive to the length of the time period being measured. As the time period grows, so do the total GRPs.
GRPs can be used to compare the same or differing time periods. When comparing GRPs for different time periods, length of the time periods should be taken into consideration.
FORMULA: Quarter or half-hour ratings are added together for the program or daypart being examined. For its sweep reports, TRAC Media computes Nielsen ratings into half-hour GRPs. TRAC’s overnight service provides GRPs based on quarter hours.
To get the GRPs for dayparts, multiply the average quarter-hour rating by the number of quarter hours. If WPBS has a quarter-hour rating of 2.5 for prime time, WPBS’ GRPs equal 2.5 multiplied by 84 (the number of quarter hours in prime time over a week) or 210.
If one station has 210 GRPs and another station has 105 GRPs, then the first station has twice as much viewing as the second.
EXAMPLE: The ratings by quarter hour for a Masterpiece episode are 1.5, 2.1, 2.2, and 1.8. The GRPs are 7.6. The ratings for Washington Week are 0.8 and 1.7 for its two quarter hours, and the GRPs are 2.5.
DEFINITION: The percentage of all households (HUTs) or persons (PUTs) using television. HUTs/PUTs are computed for time periods (e.g., 8-9 pm). (HUTs/PUTs are also known as Total TV Use.)
PROGRAM OR DAYPART? HUTs/PUTs are plotted across time periods such as days or weekends. HUTs/PUTs are rarely used for programs. More about HUTs/PUTs: HUTs/PUTs are useful in monitoring the overall ebb and flow of TV audiences.
HUTs differ by season, being the highest in the winter months and the lowest in the summer. HUTs also vary by the time of day and day of the week.
Nielsen provides HUT/PUT levels in its rating materials. HUT levels include all viewing to local stations, cable, satellite television and stations outside the DMA that spill into the market.
FORMULA: Total the ratings for all television programming sources in a time period. This includes viewing of cable services, satellite and adjacent market stations spilling into the market.*
* This will exceed the HUT slightly due to second set use in some homes
DEFINITION: The percentage of households viewing a program based on the total homes in a market. Ratings are usually generated by the quarter-hour and averaged to obtain either a program or daypart rating. (Ratings are also known as Program Popularity, Minute-By-Minute Ratings.)
PROGRAM OR DAYPART? Reported for all programs and dayparts. More about Ratings: Ratings are insensitive to the length of the program or time period, since they are averaged across quarter hours. A two-hour movie and a 30-minute news show can have the same ratings even though their cumes and GRPs might differ by a wide margin. (See separate definitions of Cumes and GRPs.)
The traditional broadcast measure is the household rating. However, more sophisticated applications use demographics, such as ratings for children 2 to 5 years or men 18 to 49 years, to ascertain whether a program reached its target audience.
FORMULA: The number of homes viewing a program or a daypart on a station divided by the total number of television homes. The quotient is then multiplied by 100 and rounded. Note that the denominator includes all homes, whether or not they are viewing television.
EXAMPLE: The smallest unit measured is the quarter-hour. The rating for a 30-minute program is actually the average of the two quarter-hour ratings.
For example, 10,000 homes viewed Washington Week between 8:00pm and 8:15pm, and 20,000 homes viewed between 8:15pm and 8:30pm. Each quarter-hour viewing is divided by the total number of television homes in the market (usually metro or DMA households), in this case 1,200,000. The rating for the first quarter-hour is 0.83 (10,000/1,200,000 x 100); the second quarter-hour is 1.67 (20,000/1,200,000 x 100). The program average rating is 1.25.
DEFINITION: The percentage of homes using television that view a particular program or daypart. A share differs from a rating because it has a different denominator.
For a share, the denominator is the number of homes using television (HUT) during the telecast of the program or daypart. (Shares are also known as Market Share, Program Appeal, Drawing Power.)
PROGRAM OR DAYPART? Provided for dayparts and programs. More about Shares: The share is always higher than the rating. Shares reflect the number of homes viewing television at the time. Sesame Street can get a 50 share on a Sunday morning because only 5,000 television sets are turned on. At other times, Sesame Street might get a three share despite having five times as many viewing households.
Shares should only be compared in similar time periods since their denominators (HUTs) fluctuate depending on the day, time or month. Ratings can be compared across dayparts or sweeps since their denominators (Total Homes) never change.
FORMULA: The number of homes viewing a program divided by the number of homes viewing television at the time. The result is multiplied by 100 and rounded.
EXAMPLE: Washington Week was viewed by 15,000 homes. The total number of homes viewing broadcast or cable in the market during the time period was 500,000 homes. Thus,15,000/500,000 x 100 = a 3 share.
*Total shares at any given time in a market usually add to slightly more than 100 due to second set usage in some of the market’s households.
AUTOMATIC CONTENT RECOGNITION (ACR): Hidden or masked audio or video codes (aka watermarks) placed in the TV signal so content can be identified.
BROADBAND ONLY (BBO): A household that neither subscribes to cable/satellite nor has an antenna… all TV/Video arrives at the home via the internet. The home may have Live streaming via YouTube TV, Sling, Hulu, Fubo, etc.
CODE READER: Nielsen’s measurement technique using a modified cellphone that monitors tuning by listening to audio codes (aka watermarks)
DAYPART: A daypart is a specific portion of a week for which ratings are reported. For example, in the Eastern Time Zone prime time covers Monday through Sunday 8-11pm and early fringe includes Monday through Sunday 5-8pm
DIARY MEASURE: Primarily using the telephone, Nielsen recruits a sample of homes that keep records of their TV viewing in a one-week diary. Diaries are mailed to respondents and then mailed back to Nielsen for tabulation. The diary keepers are asked to enter call letters, channel positions, program titles, and persons in the home who watched. Since diaries cover only a one-week period, four separate samples of homes are used for each sweep. The Nielsen diary week begins on a Thursday and concludes on Wednesday.
DMA OR DESIGNATED MARKET AREA: DMAs are markets which are named according to their principal city. All counties in the U.S. are assigned to only one DMA by Nielsen. A county is assigned if the DMA’s TV stations account for 50% or more of the county’s TV viewing.
LOCAL PEOPLE METER OR LPM MEASURE: In households in the largest markets, TV set tuning is monitored each minute by electronic household meters. Panelists use a remote control to report who in the household is viewing. Using this method, demographic and household information is collected simultaneously.
LPMs produce slightly reduced PUT levels and lower viewing levels for public TV stations. However, Nielsen asserts that LPMs are more rigorous than household meters because Nielsen uses more controls when selecting the LPM sample, recruits more households to participate, and the panel is turned over every two years as opposed to every five years under the old method.
METRO: Metro consists of the more urban, central counties of a market.
NSI OR NIELSEN STATION INDEX AREA: The NSI area includes all counties required to account for 95% of viewing to the DMA’s home stations. The NSI area covers Metro, DMA and fringe counties. These fringe counties lie outside the DMA but still contribute viewing to the DMA’s home stations. The fringe counties contributing most viewing to the DMA are added to the Metro and DMA counties one by one until the 95% threshold is reached.
OVER THE AIR (OTA): Reception of a TV signal via an antenna rather than cable or satellite.
PORTABLE PEOPLE METER (PPM): A small meter device worn by an individual that monitors the audio in TV and radio content and listens for Nielsen audio watermarks (ACR).
RETURN PATH DATA (RPD): Set-top box viewing data returned by cable or satellite delivery devices. Nilsen uses this data to create ratings or supplement metered data in some markets.
RETURN PATH DATA PLUS MARKETS (RPD+): Former diary markets now measured with return path data and National People Meter (NPM) homes in each DMA.
SET METERED MARKET (SMM): A market where turning is measured passively by a set-top metering device using ACR and tuning (set on/off).
SET METER MEASURE: In many larger markets, TV set tuning is monitored each minute by electronic household meters. The information is communicated electronically to Nielsen daily. Meters report more viewing than diaries simply because diary keepers forget to record all viewing. This meter method collects household viewing information only. Person ratings for metered markets are a combination of diary-derived age/sex information and household meter data. Households can drop out of the panel at any time, but Nielsen retires them after five years.