Numbers 101
Why We Use Quantcast For TV Website Traffic Data
Common Terms:
TV HHs: the Nielsen estimate of the number of television households in the USA
PERS 2+: The Nielsen estimate for the number of people aged 2 and over in the USA
LIVE+SD: The number that watched a program either while it was broadcast OR watched via DVR on the same day the program was broadcast (kind of, see below)
LIVE+3: The number watched while a program was broadcast or via DVR within 3 days of original broadcast
LIVE+7: Same as above, but 7 days rather than 3.
Ratings: Nielsen uses a ratings point system. 1 ratings point = 1% of the Nielsen estimate for the category being measured (more detail below).
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It is our goal to demystify the #s wherever possible. Here are some helpful numbers to keep in mind.
Nielsen uses a ratings point system. One rating point = 1% of the Nielsen universe. There are multiple Nielsen Universes.
TV HHs= Households with TVs =112,800,000 – this is the # of total households with televisions in the US estimate being used for the 2007-2008 season.
Pers 2+ = # of people age 2 and up=286,300,000 –this is the estimate of the total number of people age 2 and over in the US for the 2007-2008 season.
These are the two basic sets of numbers that drive the generally available ratings which Nielsen releases.
Keeping in mind that a ratings point is 1% of the universe, all of the aggregate ratings you see are calculated against these two numbers. Nielsen provides ratings for both TV HHs AND Pers 2+. Since these are two different sets of numbers, the lists can be very confusing.
If you see a HHs rating of 6.2, that means 6.2% of the households were tuned into that program. The math works like this:
6.2% of 112,800,000 = 6,993,600 TV HHs were tuned in.
While TV HHs are a good proxy for how many people are watching, Nielsen also tracks how many people in each household were watching a show. Sometimes you may see something with a VIEWER or Pers 2+ rating. These numbers are just a percentage of the 286,300,000 people estimate.
At TVbytheNumbers, we strive to simplify as much of this as possible by focusing on total viewers wherever possible. We do this because while there are uses for the other numbers, we believe the most important number to the people producing the content, the advertisers and the fans is the actual number of people who saw the show.
Whenever we have the data available for viewers, we use that and rank our lists accordingly. Typically, the “Top Shows” rankings Nielsen sends out are ranked by TV HHs ratings and not ranked by the total number of viewers. Since we believe that the number of viewers is the most important number, we sort our rankings by viewers, not households. As a result, even though we use the same numbers, our lists may look a little different than other lists you see available.
Different shows have different numbers of people per household watching. It’s not the same for every show. So it’s very possible for one show with less households to have more viewers. It happens all the time. Again, we seek to eliminate that complexity by focusing on viewers and ranking our lists accordingly.
Nielsen further breaks their universe estimates for Pers 2+ into age groups (2-11, 18-34, 25-54, etc.). The particular age group ranking generally available is the 18-49 demographic. For the 2007-2008 season, this equals 131,050,000 (or less than HALF of the total universe of 286,000,000).
Advertisers tend to like the 18-49 and 25-54 brackets. Currently we only have access to data segmented by 18-49.
Has your head popped off from thinking about all of this yet? If not, read on.
LIVE+SD = the numbers for live viewing plus same day DVR (digital video recorder) usage. It’s a bit complicated though because the typical day is from Midnight to Midnight, the SD for DVR usage runs 3AM-3AM. Huh?
To simplify this, if you have Heroes on your DVR that was recorded at 9pm, as long as you watch it prior to 3AM, it will count in the LIVE+SD numbers. So same day isn’t exactly the same day, but they always measure this the same, so it’s consistent. If you don’t watch until 4am (why are you still awake at 4am!?) it will not count in the LIVE+SD number but it will count in the LIVE+3 (live usage plus 3 days worth of DVR usage) and the LIVE+7 numbers.
