Question: With all the homes that have multiple TVs, VCRs and gadgets like TiVo, how accurate are the ratings that are used to determine the success or failure of a television show? I know that in my home and that of my father, there are several instances where we record one channel while watching another so that we don't miss shows that are on opposite each other. — Beverly W.

Televisionary: Good question, Beverly, and the folks at Nielsen Media Research, which provides the numbers on which your favorite shows live and die, have thought of — and tackled — just that problem. For the benefit of those who aren't as familiar as you may be with the process, though, I'll give a very general outline of how it works before diving into your answer.

Nielsen's national ratings are obtained using what's called a representative sample of the nation's TV households, since polling each and every one of the estimated 99 million households with TVs in them would present some fairly obvious expenses and obstacles. The idea is that with more than 5,000 houses (and more than 13,000 viewers in them) in the sample, which are randomly chosen to provide a mix of people who represent a wide range of demographics and towns, the number crunchers can say with confidence that the percentage of sets tuned to various shows paints a picture of what the whole country is watching at a given time, within a tolerable range of error.

The company measures who's watching what in several ways. Technicians install meters on every video device in the home — TV sets, cable boxes, VCRs, satellite dishes, etc. — to get a handle on which shows each is tuned to, and the company uses "people meters" to keep track of which person in the house is watching. In addition, Nielsen employs diaries and other methods to gather numbers on a market-by-market basis. So the short answer for you is: They've got it covered. If you live in a Nielsen household and you're watching, they know. They always know.

That said, of course, there are those within the industry who question Nielsen's methods and numbers, particularly those who think they're getting shorted on audience estimates. But there's really no other game in town since, love it or hate it, all must agree on a standard of measurement for telling advertisers how many people are watching. I hope that answers your question, but if you want to get the more detailed answer, you're welcome to take a look at Nielsen's own site, which includes a list of Frequently Asked Questions about its business. (Just make sure you come back here when you're done, y'hear?)