Public Opinion Quarterly Advance Access originally published online on February 1, 2008
Public Opinion Quarterly 2008 72(1):114-124; doi:10.1093/poq/nfn004
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How Too Little Can Give You a Little Too Much
Determining the Number of Household Phone Lines in RDD Surveys
Address correspondence to Daniel Merkle; e-mail: daniel.m.merkle{at}abc.com
Accurately assessing the number of household phone lines in random-digit dialed (RDD) surveys for use in weighting has become more complicated over time. This study evaluates phone line weighting by asking an in-depth battery of seven questions designed to measure the number of available land lines in the home more precisely. The results show that this weighting correction is not so simple, and that inadequately parsing the type and use of household phone numbers produces an inaccurate weight. Failing explicitly to remove irrelevant phone numbers, especially cell phones, produces a larger-than-appropriate weighting adjustment. Potentially more important on a practical level is that, when done correctly, and even when "overdone," phone line weighting had little impact across a diverse set of opinion and demographic variables.
DANIEL MERKLE AND GARY LANGER are with ABC News, 147 Columbus Ave, 4th Floor, New York, NY 10023, USA. This is a revised version of a paper presented at the annual conference of the American Association for Public Opinion Research, Phoenix, AZ, USA, May 13–16, 2004.