Activity Diary (Disability)

Both collect data from daily life, but they capture different things. Ecological momentary assessment prompts people to report their state at specific moments to capture fluctuating symptoms in real time. An activity diary instead records the sequence and duration of activities across a day, together with their location, assistance, and barriers, producing a time budget of participation. EMA is best for momentary dynamics like pain or mood, while the activity diary is best for understanding how time is allocated and how fully a person participates in life domains under real-world conditions.

The World Health Organization's International Classification of Functioning, Disability and Health frames disability as the interaction between a person and their environment, expressed through Activities and Participation domains and shaped by environmental factors. An activity diary supplies exactly the raw material this framework needs: it records activities (which map to ICF domains such as mobility, self-care, and community life), the assistance used, and the barriers encountered (which map to environmental factors). Aggregating diary data by ICF domain turns daily logs into standardized participation indicators comparable across people and studies.

It depends on how variable the person's days are and on the research question. A single day captures a snapshot but can be unrepresentative because participation varies with weekdays versus weekends, health fluctuations, and circumstances. Many disability studies collect several days, often including both weekday and weekend days, to estimate typical participation and capture variability, accepting the added respondent burden. The right number balances the need for a representative time-use estimate against the realistic capacity of respondents to record their days accurately.