Optimum Cluster Designs within a Primary Unit Using Combined Telephone Screening and Face-to-Face Interviewing

Abstract

Telephone samples are widely used for screening to locate special subgroups in the population where the final interview will be conducted face to face. This article discusses the conditions when this method is more efficient than face-to-face screening. An analysis of cost functions indicates that the phone methods will be more efficient unless the homogeneity within the cluster is small, the density of interviews is low, and/or the locating and screening costs are low relative to the cost of the interview.