The Nielsen Ratings: Just Who, Exactly, Participates?

Ann Althouse is upset -- a favorite TV show of hers has been cancelled.  One new fall TV show was just cancelled after just two episodes.  It is highly likely that the Nielsen ratings played a role in these tragic events.  The decisions about what entertainment we watch on TV are driven by the Nielsen ratings.  I have always wondered about the accuracy of the Nielsen ratings.  Many of the Nielsen information gathering techniques seem quite cumbersome, and I assume that the compensation for people’s efforts can’t be all that great.  From the Nielsen website:

What techniques do you use to collect viewing information?

Nielsen Media Research uses People Meters, set-tuning meters, paper diaries, and telephone interviews (called telephone coincidentals).

People Meter

The People Meter is an electronic metering system placed in randomly selected households – 5,000 households for nationwide audience measurement. The meter measures three things – the tuning station of the TV set (on, off, time), what channel/station is being tuned, and who is watching. The People Meter is used to produce household and persons audience estimates for broadcast and cable networks and nationally distributed barter-syndicated programs.

Who is watching television is measured by the "People" part of the meter. A fixed box is placed on or near the television, and each member of the household is assigned a personal viewing button (often, a remote clicker is also personalized). These personal buttons, allow Nielsen Media Research to determine "who" is watching which program.

Set-Tuning Meter

In 49 of the nation’s largest markets, an electronic metering system is used by Nielsen Media Research to provide set-tuning information on a daily basis. The TV-set-tuning information is collected from a sample of homes in these 49 markets (separate than the People Meter), and overnight household tuning ratings are reported on a daily basis for these local areas. This meter is placed onto the back of each television set in the home and monitors the tuning status of each TV set in the household.

Diary

Diary measurement is used to collect viewing information from sample homes in every television market in the United States. Each year we process approximately 1.6 million paper diaries from households across the country for the "sweeps" ratings periods. The standard report months – the "sweep" months – include November, February, May and July of each year.

The paper-viewing diaries are mailed out to randomly selected households in all 210 local markets in the U.S. Each household’s member in the diary sample is asked to write down what programs and channels they watch over the course of that one week.

So families must agree to have their TV watching monitored 24-7 (or to keep extensive diaries about it) and cannot tell anybody about this (Nielsen requires that those it monitors keep the fact confidential) -- all for a small amount of money.  Why would anybody want to do this?  Are the type of people who choose to do this really representative of the TV-watching population as a whole?