Panel research in which respondents complete diary sheets about items bought, programs watched or listened to, journeys made as appropriate to survey. Usually form of continuous research.

Diary technique is a traditional method of collecting audience data (readers, viewers, listeners) used by the various research companies. Sent to sample audience members, the diaries are maintained over a specific period for a fee paid by the research company. Respondents are asked to record some demographic information and also the viewing, listening, reading, and purchasing habits of each family member. Provided that the respondents keep accurate records, the diary technique yields very detailed information as to who comprises an audience, for how long, and to what extent.