What is a
RATING? What is a SHARE? It will be essential for students to understand
these terms before they will understand the Nielsen ratings weekly report.
You may wish to download, or have your students read these two articles: RATINGS
SHARE
The following is taken from the NielsenMedia.com website:
Ratings
101
Rating (RTG
or AA%):
The estimate of the
size of a television audience relative to the total
universe, expressed as a percentage. The estimated
percent of all TV households or persons tuned to a
specific station. In the example below, three of the
10 homes in the universe are tuned to channel 2. That
translates to a 30 rating.
Share (SHR):
The percent of the
Households Using Television (HUT) or Persons Using
Television (PUT) which are tuned to a specific program
or station at a specified time. Using the example
above, channel 2 is being viewed in three of the six
homes using television. That means it has a 50 share
of audience.
Gross Rating
Points (GRPs) or Target Rating Points (TRPs)
The sum of all rating
points achieved for a particular period of time and/or
schedule of commercials or spots (called Gross
Impressions when expressed as the sum of all exposures
to a given time period or spot schedule). The chart at
the bottom of the following page illustrates reach and
frequency. Each home shows which days the set was in
use during the time a commercial or spot aired. Since
each home comprises 10% of the universe of 10 homes,
each represents a 10 rating every time the spot airs.
By adding these ratings we arrive at the total of 150
Gross Rating Points.
Reach (Cume)
The number of
different or unduplicated households or persons that
are exposed to a television program or commercial at
least once during the average week for a reported time
period. During the course of the schedule illustrated
on the next page, seven different households were
exposed to the commercial at least once. Since each
home represents 10 % of the universe, this makes the
reach or cume 70%.
Frequency
Average number of
times a household or a person viewed a given
television program, station or commercial during a
specific time period. In our example, the Gross Rating
Points achieved (150) is divided by the percent of
homes reach (70) to determine the frequency of 2.1.
Frequency
Distribution
Number or percentage
of households or persons that are exposed to a given
program, station, or commercial one time, two times,
three times, etc.


Here is a simple way to explain these two concepts:
(NOTE: both RATING and SHARE are PERCENTAGES.)
RATING = households tuned in to a given program
all households with television
(more simply: rating points
measure the number of households watching programs at a given time)
SHARE = households tuned in to a given program
all households tuned in to TV at that time (HUT)
(more simply: share points measure the percentage
of all sets in use at a given time watching a particular program)
Here's an example: Your talk show is aired in a market that has 1 million
television households; 400,000 are tuned in to you. Therefore:
400,000
1,000,000 = .40, or a rating of 40
At the time your show airs, however, there are only 800,000 households using
television. Therefore, your share of the available audience is
Share = 400,000
800,000 = .50, or a rating of 50
If you can explain why a specific program's share is always higher than its
rating, then you understand the difference between the two.
(source: Introduction To Mass Communication, by Stanley J. Baran,
McGraw Hill, 2001 pg. 280)

