Media-Use Diary Method

Interval-contingent diaries ask for entries at fixed intervals, such as each evening, suiting reflective summaries. Signal-contingent diaries prompt entries at random or scheduled signals, capturing momentary states (this overlaps with experience sampling). Event-contingent diaries ask for an entry whenever a defined event occurs, such as each time the participant uses social media, capturing rare or specific behaviors. The choice depends on whether the phenomenon is continuous, momentary, or event-based, and on how it is distributed in time.

Diary studies produce many observations per person, so entries from the same individual are correlated rather than independent. Ordinary regression that ignores this clustering underestimates standard errors and conflates within-person and between-person effects. Multilevel (mixed-effects) models nest occasions within persons, with random intercepts and slopes, allowing researchers to separate how a person's media use varies across occasions from how people differ from one another — the central questions diaries are designed to answer.

They overlap heavily and are sometimes used interchangeably. Experience sampling is essentially a signal-contingent diary that prompts participants at random or scheduled moments to report their current state, emphasizing momentary, in-the-moment experience. The diary method is a broader umbrella that also includes interval-contingent (e.g., end-of-day) and event-contingent reporting. In practice, smartphone-based studies blur the line, combining scheduled prompts with event-triggered and end-of-day entries.