the problem of “forgetting.” The “short cue” version of the instrument that resulted from the research attempted to provide a rich set of cues for each victimization type. In this regard, a marriage between the incident report and the screening questions was key. The screener questions were designed to maximize recall, even at the risk of overreporting incidents through duplicate reports about the same event or misdating of an event that occurred outside the reference period. The role of the incident reports was to duplicate those reports.
The finding that forgetting was a function of the salience of the event to the person and the length of time since the event implied that smaller victimizations occurring further back in time were most fraught with reporting errors. The length of the reference period (the time from the start of the eligible time period for events to be in scope to the end of the period) and the length of the recall period (the time between the start of the in-scope period and the day of the interview) were issues that could affect the quality of reports. Longer periods yielded poorer reports (Miller and Groves, 1985; Czaja et al., 1994), generally a mix of forgetting and misdating events. The redesign recommended a 6-month reference period, a recommendation based on the findings of increased measurement error due to forgetting and telescoping in 12-month reference periods.
There was another antidote to misdating or telescoping errors, which was already in place in the NCS—the use of a bounding interview. A bounding interview in the context of the NCS was the first wave interview with each respondent, in which events in the 6-month reference period before the interview were reported. No data from the bounding interview were used in estimation (another recommendation stemming from findings of forward telescoping errors). Instead, the events reported in the bounding interview were made known to the second wave interviewer to verify that a incident reported in that interview was not a duplicate of a report in the first, bounding interview. This was thought to reduce forward telescoping errors in the NCS estimates. Some research in the redesign focused on whether the data from the bounding interview might be integrated through statistical models into the estimates, but that never led to such a recommendation.
The panel notes that the design features of the reference period, the cuing mechanisms of the screener questions, the nature of the incident reports, and the use of the bounding interview technique are mutually connected. It is difficult to evaluate one of these features without simultaneously considering the others.