Sample Management

Sample Management in Interviewer-Administered Surveys

In interviewer-assisted surveying, both for in-person and telephone surveys, sample management can be viewed as being composed of two primary responsibilities that often are in direct conflict with each other. One of these responsibilities is to allocate enough sample cases to keep interviewers productive and, in turn, to employ the right number of interviewers to process the sample so as to achieve the number of completed interviews that are required for the survey within the field period. The other responsibility is to activate “just enough” cases so that the field period ends with the highest possible response rates at the lowest possible cost.

Based on past experience, the sample manager of an interviewer-administered survey will have an informed expectation of approximately how many sample cases will need to be activated from the available sample (i.e. the sampling pool) during the survey field period to achieve the required sample size of completed interviews. Oftentimes the sample will be divided into sample replicates, each containing random subsets of cases. Once a replicate of cases has been activated, the entire replicate must be fully processed to allow each case to reach its proper final outcome.

If cases are not worked enough during the field period, response rates will suffer. Thus, the sample managers need to activate the last replicate of cases, leaving enough time in the field period to allow those cases to be processed fully. If not enough time is left to process this final set of cases, the most hard-to-reach respondents within those cases will not be contacted and interviewed. In contrast, if cases are contacted too frequently during the field period, for example, by having an overabundance of interviewers constantly making contact attempts, response rates also will suffer because respondents will become annoyed if the survey organization contacts them too frequently. Thus, the challenge for the sample managers is to have the right number of sample cases active at any one time and the right number of interviewers scheduled to process these cases.

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