Telephone surveys are not suitable for all purposes. Once complexity arises, interviews may need to be conducted in personal detailed interviews that can be recorded and analyzed, written or telephone surveys do not have the advantages needed. First, in-depth interviews may take up to an hour, as there are typically more questions. Also, interviews that take place on-site, for example, at trade fairs, allow the target group to be asked directly. The interviewer may also require pictures or lists to illustrate issues, and where necessary, give assistance.
A special kind of personal interview is the CAPI method (Computer-assisted Personal Interviewing), which the survey is carried out on an electronic device (A Pocket PC). The device offers better presentation over traditional paper documents. This also enables films, advertising or other sequences to be shown. Further, the technology also allows the data to be stored directly on the device, shortening the survey period. Later, the data can be exported easily to the desired analysis programs- this technology can save time and money.