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Using Security Questions to Link Participants in Longitudinal Data Collection

NCJ Number
Prevention Science Volume: 21 Issue: 2 Dated: 2020 Pages: 194-202
Date Published
9 pages

Since anonymous data collection systems are often necessary when assessing sensitive behaviors but can pose challenges to researchers seeking to link participants over time, this article assists researchers in anonymously linking participants by outlining and reporting the results of testing a novel security question linking (security question linking; SEEK) method. 


The SEEK method includes four steps: (1) data management and standardization, (2) many-to-many matching, (3) fuzzy matching, and (4) rematching and verification. The method is demonstrated in SAS with two samples from a longitudinal study of adolescent dating violence. After an initial assessment during a laboratory visit, participants were asked to complete an online assessment either (a) once, 3 months later (Sample 1, n = 60), or (b) three times at 1-month intervals (Sample 2, n = 140). Demographics, eye color, and responses to nine security questions were used as key variables to link responses from the laboratory and online follow-up assessments. The rates of matched cases were 100 percent in Sample 1 and from 94.3 to 98.3percent in Sample 2. To quantify the confidence in the data quality of successfully matched pairs, the means and standard deviations of the number of matched security questions are reported. In addition, the article reports the rank order and counts of the mismatched components in key variables. Results indicate that the SEEK method provides a feasible and reliable solution to link responses in longitudinal studies with sensitive questions. (publisher abstract modified)

Date Published: January 1, 2020