CBS News Polls: Who we talk to

CBS News Poll polls pie chart

Who do we talk to?

Most CBS News/New York Times surveys are done by telephone. Anyone 18 years or older living in the continental United States is eligible to participate in our surveys.

How do we choose the people we interview?

In a nutshell, we choose the people we interview completely at random. We do not choose our respondents based on their age, race, political philosophy, or any other characteristic.

In fact, when we reach people at home, we have no idea who they are or what categories they fall into. We only know one thing about them - their telephone number.

How do we get those telephone numbers?

A computer chooses the telephone numbers of these people for us, and it does so essentially at random.

The process that the computer uses is called "random-digit dialing." We tell the computer the area code and the exchanges of every telephone in the United States. First the computer chooses a group of area codes and exchanges at random. Once it selects these exchanges, it then picks the last four numbers effectively by chance.

Why do the telephone numbers have to be random?

We go to great lengths to make sure that the numbers are picked as randomly as possible. Why is that important? It assures that we get old and young people, rich and poor people, conservative and liberal people - and everybody in between.

Let's say the computer is about to pick a telephone number from your area code and telephone exchange. There are 10,000 possible telephone numbers. So the odds are one in 10,000 that the computer would pick your telephone number if your exchange were in the sample.

But here's the important part: your neighbors would also have exactly that same chance of being selected. Everyone in your neighborhood has the same chance as everyone else of being called in our survey. And the same is true of everyone with a telephone in the United States. That's why we can say that our surveys generally represent the opinions of the whole country.

Do people with unlisted telephone numbers get called too?

Yes, and so do people who have moved recently but whose numbers are not in the telephone book. By picking telephone numbers at random, we don't have to rely on telephone books to choose our respondents.

Anyone with a telephone in his or her home or a cell phone has an equal chance of being called by our interviewers. That only leaves out the few people in the United States who do not have telephones, and those people make up a small portion of the public.

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    Sarah Dutton is the CBS News director of surveys.