Abstract:
Objective: To identify any differences in response and completion rates across
two versions of a questionnaire, in order to determine the trade-off between a
potentially higher response rate (from a short questionnaire) and a greater level of
information from each respondent (from a long questionnaire).
Methods: This was a randomised trial to determine whether response rates and/or
results differ between questionnaires containing different numbers of choices: a
short version capable of estimating main effects only and a longer version capable
of estimating two-way interactions, provided certain assumptions hold. Bestworst
scaling was the form of discrete choice experimentation used. Data were
collected by post and analysed in terms of response rates, completion rates and
differences in mean utilities.
Results: Fifty-three percent of individuals approached agreed to take part. From
these, the response to the long questionnaire was 83.2% and the short questionnaire
was 85.1% (difference 1.9%,95% CI -7.3,11.2; P = 0.68). The two versions
of the questionnaire provided similar inferences.
Discussion/conclusion: This trial indicates that, in a healthcare setting, for this
complexity of questionnaire (i.e. four attributes and the best-worst scaling design),
the use of 16 scenarios obtained very similar response rates to those obtained
using half this number.
