Search This Blog

Tuesday, July 21, 2015

Survey Nonresponse

In a Pew interview, Scott Keeter talks about response rates in surveys:
The potential for what pollsters call “nonresponse bias” – the unwelcome situation in which the people we’re not reaching are somehow systematically different from the people we are reaching, thus biasing our poll results – certainly is greater when response rates are low. But the mere existence of low response rates doesn’t tell us anything about whether or not nonresponse bias exists. In fact, numerous studies, including our own, have found that the response rate in and of itself is not a good measure of survey quality, and that thus far, nonresponse bias is a manageable problem.
For example, our 2012 study of nonresponse showed that despite declining response rates, telephone surveys that include landlines and cellphones and are weighted to match the demographic composition of the population (part of standard best practices) continue to provide accurate data on most political, social and economic measures. We documented this by comparing our telephone survey results to various government statistics that are gathered with surveys that have very high response rates. We also used information from two national databases that provide information about everyone in our sample – both respondents and non-respondents – to show that there were relatively small differences between people we interviewed and those we were unable to interview.
We are obtaining nearly identical response rates on landline phones and cellphones. However, it takes considerably more interviewer time to get a completed interview on a cellphone than a landline phone, because cellphone numbers have to be dialed manually to conform to federal law. In addition, many cellphones are answered by minors, who are ineligible for the vast majority of our surveys. Unlike a landline, we consider a cellphone a personal device and do not attempt to interview anyone other than the person who answers.