Introduction

The getting of information begins with an act of response, and for good reasons, statisticians have long been concerned about problems of response to surveys and polls. The most elementary source of concern is simply that people may refuse to respond or may neglect to do so. In the early years of social research and political polling, the novelty and even gratification at being asked an opinion on some issue may well have been sufficient to induce participation. Such times are passing. Many authors (e.g., Hawkins, 1977; Brooks and Bailar, 1978; Martin, 1983) have noted the secular decline in the response rate to surveys. Hawkins notes that nonresponse rates, largely due to refusals, have increased secularly at annual rates approaching 1 percent. The most immediately recognizable consequence of a low response rate is a corresponding loss of precision with increased sampling variability of estimators and loss of degrees of freedom in hypothesis testing. We have already remarked on a further problem associated with a low response rate as such. Even if the sample size is nevertheless formally sufficient to accept or reject the appropriate null hypothesis at apparently reasonable levels of significance, the statistician may experience considerable difficulties in getting the conclusions accepted by his or her readership. The precise-difficulty may vary according to the survey subject and the readership. It may arise in connection with perceived problems of nonneutrality of a kind to be considered shortly.