1. Use the first wave results for housing units to modify retention probabilities for the second wave, so that housing units that report victimization in the first wave are more likely to be retained.

Recommendation 4.7: BJS should investigate changing the sample design to increase efficiency, thus allowing more precision for a given cost. Changes to investigate include:

  1. changing the number or nature of the first-stage sampling units;

  2. changing the stratification of the primary sampling units;

  3. changing the stratification of housing units;

  4. selecting housing units with unequal probabilities, so that probabilities are higher where victimization rates are higher; and

  5. alternative person-level sampling schemes (sampling or subsampling persons within housing units).

Other Improvements

In early redesign efforts in the early 1990s, a consistent finding that CATI interviews yielded higher reports (Hubble, 1999) led to the belief that CATI interviewing could both save money and obtain higher quality data. Now that the dispersed interviewing of the NCVS uses computer-assisted personal interviewing, the role of CATI in the overall cost-error structure of the NCVS is worth reconsidering. Both CATI and CAPI can use the same software for automatic routing and editing of responses, and the only distinction between the two approaches is connected with (a) different interviewers and (b) centralization of CATI that might affect impacts of supervision.

There are time and administrative costs from shifting cases to and from CATI facilities to field interviewers in cases in which the mode initially assigned is not desired by the respondent. These tend to reduce the response rates of the NCVS. It seems likely that the cost-quality attributes of the NCVS might be improved by shifting all telephone calling to interviewers’ homes.

Recommendation 4.8: BJS should investigate the introduction of mixed mode data collection designs (including self-administered modes) into the NCVS.

As with most federal household surveys, the person-level response rates (known as Type Z rates in the NCVS) are declining over time. Whether these declines have produced estimates with higher nonresponse bias is not clear from the data at hand. Increasing evidence from survey methodology

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