Examining the Concurrent and Predictive Validity of Single Items in Ecological Momentary Assessments

While single items can save time and burden in psychology research, concerns about their reliability have made the use of multiple-item measures the default standard practice. While single items cannot demonstrate internal reliability, their criterion validity can be compared to multiple-item measures. Using ecological momentary assessment data, we evaluated repeated measures correlations and constructed multilevel cross-lagged models to assess concurrent and predictive validity of single- and multiple-item measures. Correlations between the single- and multiple-items measures ranged from .24 to .61. In 27 out of 29 single-item predictor models, single items demonstrated significant predictive validity, and in one out of eight sets of comparisons, a single-item predictor exhibited a larger effect size than its multiple-item counterpart. While multiple-item measures generally performed better than single items, the added benefit of multiple items was modest in most cases. The present data provide support for the use of single-item measures in intensive longitudinal designs.