10/13/2009 10:27 am ET | Updated May 25, 2011

Random Sampling and 'Opt-In' Internet Panel Surveys

My column this week takes up the subject of "opt in" internet panel surveys and a recently released, much debated accuracy study by a team of Stanford researchers. As this subject is too big for a single column, I've split it into two parts. This week, in Part I, I take up the issue at the heart of the controversy: random probability sampling.

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