Ratings Info

Detailed info on how ratings are determined.

Info originally gathered and posted by Clint.
Reposted here for archival purposes

The following Information was derived from:

Nielsen's Media

Metered Markets - Ranked by DMA Size

Book: Media/Impact - An Introduction to Mass Media Second Edition by Shirley Biagi

Total Estimated Nielsen's Boxes 5,000
Homes Represented by 1 Nielsen's Box 21,328
Average viewers per home 2.6
Total Homes 106,641,910 (As of 9/21/2002)

Example Rating 4.3/6

(First number / Second number)

First Number: Rating point represents 1,021,848 households, or 1 percent of the nation's
                            estimated 102.1 million TV homes.

Second Number: The share is the percentage of turned on televisions tuned to Roswell.

First Number: 4.3

Math Steps

1) Convert 4.3 Percent to decimal form. (4.3 divided by 100) giving .043

2) Multiply 102,184,810 (Total Homes)
     by .043 (Decimal Form)
     giving 4,393,946.83 (Total homes watching Roswell)

Second Number: 6

Math Steps

1) Convert 6 percent to decimal form (6 divided by 100) giving .06

2)  4,393,946.83 (Total Homes Watching Roswell)
      divided by .06 (Decimal form of share)
      giving 73,232,447 total televisions turned on.

If a show has a low rating and a high share, what does that mean? 

Basically means it's the most watched show in a bad time slot when not a lot
of people watch television. High share means a lot of the people who are
watching television at that time are watching that show. Low rating means
that a low percentage of all people, whether or not they are watching
television at that time, are watching that show.

Let's say in a town there are 10,000 televisions. Now let's say 1000 of
these are turned on (i.e. people are watching them) at, say, 10 AM on
Monday. And now, of these 1000 sets, 500 of them are tuned into Show A.

Now as you can see, only 5% of all TV sets in town are tuned into Show A at
that time, which is a low rating. But 50% of all the TVs turned on at the
time are tuned into Show A, which is a high share. So what low rating/high
share tells you is that not many people are watching TV at 10 AM on Monday,
but many of those who are are watching Show A.


If a show has a high rating and a low share, what does that mean?

Well, this time, let's say there are 10,000 TVs, 9,000 of which are turned
on at Thursday at 9PM, 2,000 of which are tuned into Show B. It has a high
rating, 20%, and a relatively low share, 22%. This simply means that it is
in a time slot where a lot of people are watching television. Yes, a lot of
people are watching that particular show, but a lot of people are watching
other shows as well.

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