Encuesta de CNN/TIME subestima los apoyos de Ron Paul en Iowa

Nate Silver:

The new CNN poll of Iowa contains a methodological quirk that is worth bringing to your attention and which will probably result in the survey underestimating the support for Ron Paul.

The issue is that CNN’s Iowa poll was conducted by using a list of registered Republican voters and registered Republicans only:

Sample was drawn from the complete list of registered Republican voters provided by the Iowa Secretary of State.

What’s wrong with using a list of Republican voters for a Republican caucus poll? The answer is that it’s extremely easy for independent and Democratic voters to register or re-register as Republicans at the caucus site. Historically, a fair number of independent voters do this.