The following Information was derived
from:
Nielsen's Media
http://www.nielsenmedia.com/
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.
