The Advent of Internet Surveys for Political Research: A Comparison of Telephone and Internet Samples

The Internet offers a number of advantages as a survey mode:low marginal cost per completed response, capabilities for providingrespondents with large quantities of information, speed, andelimination of interviewer bias. Those seeking these advantagesconfront the problem of representativeness both in terms ofcoverage of the population and capabilities for drawing randomsamples. Two major strategies have been pursued commerciallyto develop the Internet as a survey mode. One strategy, usedby Harris Interactive, involves assembling a large panel ofwilling respondents who can be sampled. Another strategy, usedby Knowledge Networks, involves using random digit dialing (RDD)telephone methods to recruit households to a panel of Web-TVenabled respondents. Do these panels adequately deal with theproblem of representativeness to be useful in political scienceresearch? The authors address this question with results fromparallel surveys on global climate change and the Kyoto Protocoladministered by telephone to a national probability sample andby Internet to samples of the Harris Interactive and KnowledgeNetworks panels. Knowledge and opinion questions generally showstatistically significant but substantively modest differenceacross the modes. With inclusion of standard demographic controls,typical relational models of interest to political scientistsproduce similar estimates of parameters across modes. It thusappears that, with appropriate weighting, samples from thesepanels are sufficiently representative of the U.S. populationto be reasonable alternatives in many applications to samplesgathered through RDD telephone surveys.