The Internal Revenue Service (IRS) conducted a survey of taxpayers to better understand the pre-filing and filing burden of individual taxpayers. The sampling frame was taxpayers who filed a 2007 income tax return in 2008. The overall response rate was 48% with roughly 39% of the responses via telephone, 28% via web, and 33% via mail.
In this paper we explore the differences in respondents by response mode, with particular interest in those who responded via the web as the rate for this mode was unexpectedly high. We also address the nonresponse bias and explore ways to adjust for this bias when the researcher is interested in a vector of estimates, not just one point estimate. For this study, total burden is the sum of seven separate but correlated estimates. Since we are able to link the survey responses back to the tax return, we have an especially rich data set to analyze.