Abstract
The Timeline Followback (TLFB) interview has been used extensively in the assessment of alcohol and other substance use. While this methodology has been validated in multiple formats for multiple behaviors, to date no systematic comparisons have been conducted between the traditional interview format and online versions. The present research employed a randomized within-subjects design to compare interview versus online-based TLFB assessments of alcohol and marijuana use among 102 college students. Participants were randomly assigned to receive either the online version first or the in-person interview format first. Participants subsequently completed the second format within 3 days. While we expected few overall differences between formats, we hypothesized that differences might emerge to the extent that participants are more comfortable and willing to answer honestly in an online format, which provides a degree of anonymity. Results were consistent with expectations in suggesting relatively few differences between the online version and the in-person version. Participants did report feeling more comfortable in completing the online version. Moreover, greater discomfort during the in-person assessment was associated with reporting more past-month marijuana use on the online assessment, but reported discomfort did not moderate differences between formats in reported alcohol consumption.