When evaluating television proposals, it is important to know how the ratings data is collected, in order to understand why the ratings provided by each service will differ.
The Nielsen Company has provided the television advertising currency for many years. Rentrak began capturing local television viewing in 2009, and now has 210 stations across the country subscribing to its data in addition to or in place of Nielsen data.
The Nielsen Company measures 210 individual television markets (DMAs) in the U.S. and employs 3 types of methodology to measure viewing levels:
1. Diary Markets
“Diaries” are paper journals sent by mail to a percentage in the DMA, and the participant is asked to manually record daily viewership for one week. This is the most common method and is used in 153 markets across the country.
2. Metered Markets
31 mid-sized DMAs use a set-top meter to track household viewing. This data provides advertisers with “overnight” ratings based on the household data. The demographic data is collected through the same diary methodology, referenced above, and used for the 4 standard survey periods, February, May, July and November.
3. Local People Meters (LPMs)
In 2002, Nielsen rolled out LPMs to the top 25 DMAs. This is similar to the set-top meter in metered markets, however these devices are used to collect demographic data, so paper diaries are not necessary. TV stations and advertisers in LPM markets have access to overnight ratings by demographic (i.e. Adults 25-54).
Rentrak is currently measuring 210 markets and collects data from 8.5 million homes nationwide.
One main difference between Nielsen and Rentrak is that Rentrak’s data is 100% passive. There is no representative sample and households are not distributed proportionally throughout the market.
Sample sizes are larger than those through Nielsen, because Rentrak collects data from households subscribing to DISH Network, AT&T U-Verse and Charter services. Household viewing is measured by set-top-box data and no demographic information is collected. Households don’t even realize they are being monitored.
It is important to note, households viewing television over the air or through many cable services are not included in the Rentrak sample.
Nielsen has separate survey delivery dates, based on the methodology applied. Diary markets will receive 4 surveys a year during “sweeps” months: February, May, July and November. Metered markets follow a similar schedule, however these markets include household overnights and a handful of metered markets will also receive a survey in January and October. LPM markets receive overnight data by demographics, as well as a survey book for every month of the year.
Since Rentrak’s methodology does not require any user participation, they are able to provide consistent monitoring throughout the year.
Demographic Measuring vs. Consumer Behavior
Nielsen tracks viewing by individuals in participating households by specific demographics. They include people of all ages and ethnicities in proportion to the population. Panels are assembled that mirror U.S. Census data, so representative samples are used to project viewing across all homes. Viewing information is used to project ratings for the entire DMA population.
Rentrak on the other hand, collects household viewing from set-top data and combines it with Census information to project who is likely living in the home. They also use qualitative data from Epsilon Targeting and other third party resources to layer consumer behavior on top of television viewing. Rentrak believes demographic information is not predictive of purchase behavior, and therefore consumer behavior is much more important than basic gender/age demographics.
This means, if you are a local car dealership, you would pull a ranker for the top programs for households in the market for a new car, instead of a traditional demographic like Adults 25-54.
For local advertisers, weigh these differences very carefully. If it is necessary for you to reach a particular segment of the population with your message, make sure you are comfortable with the way the ratings have been collected and compiled.