Comparing Ecological Momentary Assessments and Time Diary Methods for Measuring Daily Life

A growing number of social scientists are using ecological momentary assessment (EMA) to observe how social forces operate in real time. However, the validity of EMA for measuring features of daily life-what people are doing, where, and with whom-remains uncertain. A key challenge is the lack of consensus across studies about how validity in EMA methods is defined and assessed. The authors address that gap by comparing EMA data (n = 1,174) with time diary data (n = 1,113) using two population-based samples. An advantage of large samples is the ability to evaluate the magnitude of bias rather than relying solely on p-values, as is common in small-sample studies. The authors find that both methods yield similar estimates of moments captured at home and in the workplace, supporting their validity in those contexts. However, EMA tends to overestimate moments spent alone compared with time diaries, likely because of moment selection bias. Moreover, large discrepancies in estimates for eating and drinking and household chores suggest that relying on primary activity reports can introduce significant bias for multitasked activities. Comparing these methods provides insight into their relative strengths and limitations, helping researchers assess the validity, potential biases, and interpretive implications of each across key domains of daily life.