CAPI relates to personal interviews but is dissimilar to CATI.

Rather than entering reponses on paper, an interviewer would key in responses from their respondent or interviewee directly into a purpose-built computer program on a small device or (decreasingly) a laptop.

For large surveys CAPI is cost effective and decreases coding and data-entry mistakes, as data need only be transcribed once and automated procedures such as response checking can immediately advise common transcription errors. In the case of the device being hooked up to the internet or WAN, results can be immediately transferred to the research office for admin or analysis.

Other advantages include less interviewer training, and speed. However CAPI is ideaaly suited for Multi-subject Street or shopping centre type intercept or maybe home interviews, where the data is mainly structured and interviews are short.