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There are companies that do surveys by phone. In addition there's a company call Neilson, that puts recording devices on people's TVs to monitor what they watch.

It based on population like any other survey is. They take a random number of phone numbers from different areas--usually chosen by computer.

2007-05-04 05:32:49 · answer #1 · answered by robert2020 6 · 0 0

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