sidered for the 2004 administration of the SCS. In the test, face-to-face and telephone interviews were conducted in parallel; the face-to-face interviews recorded a 67 percent response rate compared with 49 percent by telephone, with the difference attributed to refusals to be interviewed. When victimization estimates from the two modes of administration were compared, the telephone rates were found to be consistently higher, raising the possibility that the telephone administration had the effect of oversampling persons with incidents to report. A follow-up test recontacted some respondents from the first survey and compared victimization estimates for the group of people who responded on the first contact with those who had their refusals “converted” to responses in the second pass. Victimization rates were found to be lower for the “converted” group than the initial respondents, corroborating the hypothesis that refusals are more likely to include nonvictims (people with no incidents to report) rather than victims.

The Rise in Survey Costs

From the fiscal and operational standpoint, the major consequence of increased nonresponse is increased survey costs. These are incurred when the data collection effort seeks to maximize response rates, devoting field resources to repeated attempts to contact households for interviews. Cost inflation would be more modest if only one call were made to each household. In the NCVS and other surveys seeking high-quality estimates, repeated callbacks and efforts at persuasion are introduced on sample cases that have not yet been interviewed. Repeated calls in face-to-face surveys require the interviewer to drive to the sample unit and attempt contact. If no one in the household is at home, another call—often on another trip—is required. If a contact is achieved but the householder is reluctant to participate at the time, another call is made. What results from such a recruitment protocol is that noninterviews require more effort than interviews; the cost of a failure is larger than the cost of a successful interview. As the difficulty of making contact and gaining cooperation increases over time, the costs of the total effort increase if response rates are to be maintained.

In short, attempting to achieve high response rates in a survey of a population presenting growing difficulty in making contact and gaining cooperation will lead to cost inflation.

The Linkage Between Response Rates and Nonresponse Error

It is traditional to attempt to maximize response rates in an effort to reduce nonreponse error. This flows from a simple deterministic view of nonresponse error in a sample mean (like the number of victimizations reported divided by the number of persons) as a function of nonresponse rates and the difference between respondent and nonrespondent means. Increas-

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