Computer Assisted Telephone Interviewing (CATI) is an interactive front-end computer system (telephone surveying) that aids interviewers to ask questions over the telephone. The answers are then keyed into the computer system immediately by the interviewer. CATI is the oldest form of computer assisted interviewing. It is structured system of microdata collection by telephone that speeds up the collection and editing of micordata and also permits the interviewer to educate the respondents on the importance of timely and accurate data.

The interviewer initiates the interview sessions. The computer program controls branching to or skipping among questions, and validates the data as it is entered. The interviews are more personalized, probing questing are standardized, use of historic data is standardized, and questions can be more sophisticated than those on paper questionnaires. More complex questionnaire design is possible since the program controls branching and logic. CATI works particularly well in situations where a short implementation schedule exists.