Telephone interviews are easy to administer and allow data to be collected quickly at a relatively low cost. The interviewer can clarify the questions. Response rates tend to be higher and telephone interviewing allows for greater sample control. However, it is more expensive than a mail questionnaire. The presence of an interviewer on the phone may bias responses since respondents may be unwilling to discuss personal information. Also, respondents can’t see product. A major limitation is that they must be short.
Personal interviews may be conducted one-on-one or with a focus group. A personal interview is a direct, face-to-face interview between the interviewer and the respondent. In the past, personal interviews were conducted door-to-door. Today, most personal interviews (one-on-one) are conducted in malls and are referred to as mall intercept. Personal interviews are the most flexible since interviewers can clarify questions and probe for answers. Respondents can see a concept as well as read a description. More information can normally be obtained through observation of the respondent’s surroundings. Personal interviewing is expensive, yet it offers a great deal of flexibility and allows for visual stimuli.