  We present an approach to inform decisions about nonresponse follow-up
sampling. The basic idea is (i) to create completed samples by imputing
nonrespondents' data under various assumptions about the nonresponse
mechanisms, (ii) take hypothetical samples of varying sizes from the completed
samples, and (iii) compute and compare measures of accuracy and cost for
different proposed sample sizes. As part of the methodology, we present a new
approach for generating imputations for multivariate continuous data with
nonignorable unit nonresponse. We fit mixtures of multivariate normal
distributions to the respondents' data, and adjust the probabilities of the
mixture components to generate nonrespondents' distributions with desired
features. We illustrate the approaches using data from the 2007 U. S. Census of
Manufactures.
