Asking Questions - The Definitive Guide To Questionnaire Design ...

68 ASKING QUESTIONS
respondents (a panel study). The initial interview is unbounded,
and the data are not used for this period. At all subsequent interviews,
however, the respondent is reminded of behaviors reported
previously. The interviewer also checks new behaviors reported
with those reported earlier, to make sure that no duplication has
occurred. Thus, to prevent errors on dates, the earlier interviews
“bound” the time period.
Bounded interviews have been used successfully in a wide range
of applications. Note, however, that the effects of bounding are just
the opposite of those for aided recall. Bounding will reduce telescoping
and improve information on details but will have no effect
on omissions. If omissions are the more serious problem, bounded
interviews may even cause larger errors, since bounded interviews
eliminate compensating biases. Using both aided recall and
bounded recall should result in low actual and net biases.
The major problems with the bounding procedures now in use
are that they require multiple interviews and may be too costly and
too time-consuming for most researchers. An alternative is to use
bounding procedures in a single interview (Sudman, Finn, and
Lannom, 1984). That is, you start with questions about an earlier
time period and use the data from that period to bound the reports
of the current period. Thus, for example, in an interview conducted
in the middle of June, a respondent might first be asked about clothing
purchases during the month of May. Questions would then be
asked about clothing purchases in June, with the May date used for
bounding. Although there may be concerns of compounded biasing
(suppose the estimate for May is too high), this method provides
surprisingly accurate estimates.
Consider the Use of Secondary Records
Another method of reducing telescoping and improving information
on details is to use household records, where available (Sudman
and Bradburn, 1974). A search for records, as with a household
inventory, is best accomplished in a face-to-face interview.