On the mode of administering a questionnaire and responses to open-ended items☆

Concurrently administered personal and telephone surveys are compared to measure differences between the modes for identical questions. Speed of questioning is found to be greater in telephone interviews than personal interviews. The faster pace of telephone interviews is linked to shorter answers to open-ended items on the telephone. The tendency to reduce such responses is disproportionately exhibited by younger, affluent respondents who tend to provide detailed responses in personal interviews. In a recent experimental study of the relative efficiency of telephone and personal interview surveys, it was casually observed that the pace of the telephone interviews seemed faster than that of typical personal interviews. Although it was not always clear whether the respondent or the interviewer set the pace, it was hypothesized that the different delivery styles might be associated with method effects between personal and telephone interviews. Since the same set of questions was asked of adult respondents on the telephone and in person, the project offered an opportunity to investigate: (1) whether the average speed of telephone interviews tended to be greater than personal interviews asking the same questions; that is, whether greater speed could be viewed as a characteristic of phone interviews; (2) whether speed of the interview is associated with method differences in the number of responses given to open-ended items; (3) whether the number of responses to open-ended items varies predictably according to the method of administration; (4) whether that variation is related to differences in the categories of responses given; and (5) whether there are subgroups of the adult population that disproportionately reflect method effects in their number of responses to openended items. Although there have been other studies which examined