We examine a post election mixed-mode (Internet and mail) survey design of 2008 general election voters in terms of its representativeness. Sampled registered voters in New Mexico received a letter about a week after Election Day requesting their participation in a post election survey and were...

We propose a novel view of selection bias in longitudinal surveys. Such bias may arise from initial nonresponse in a probability sample, or it may be caused by self-selection in an internet survey. A contraction theorem from mathematical demography is used to show that an initial bias can...