Web-based administration of the PFDI-20 and PFIQ-7 was acceptable to the women participating in this research. Moreover, the majority of participants preferred this mode of administration. We suspect that the branching pattern, which shortened the questionnaire for some participants, contributed to the preferences voiced by the women in this study. Other researchers have found that research participants voice a preference for electronic questionnaire administration.8–10, 13
The acceptability to research subjects, in conjunction with the high degree of correspondence between scores obtained through WBQ and traditional pencil and paper administration, recommends web-based administration for future research protocols.
In research involving sensitive or embarrassing information, self- administered paper and pencil questionnaires or electronic questionnaires are preferred to direct interviews. Interviews are less sensitive than self-administered questionnaires because subjects are less likely to volunteer potentially-embarrassing information.13, 14
Moreover, when comparing modes of self-administration, prior research has shown that electronic questionnaires may be more sensitive than paper questionnaires,12, 14
possibly because patients respond to the apparent “legitimacy” of the format14
or because electronic questionnaires are perceived by research subjects as more anonymous.13
In this study, we did not find that the WBQ was more sensitive than the paper-and-pencil questionnaire. Scores and subscale scores were not significantly different between modes of administration. This is reassuring, since researchers can conclude that scores obtained through one mode of administration are equivalent to scores obtained with the other mode.
Electronic questionnaires have numerous benefits to researchers. These include the ability to incorporate complex branching patterns, reduction of errors (including multiple responses to single-option items), and elimination of the need for separate data entry.11–13
While branching patterns can be incorporated into both paper questionnaires and electronic questionnaires, complex skip patterns or extensive customization may create confusion, leading to unnecessary responses to some items and/or incomplete responses to other items. Also, electronic questionnaires can be designed with automated date and time stamps,15
allowing accurate representation of when timed questionnaires or diaries are completed. The on-screen format can be designed to present questions individually, minimizing the impact of questionnaire length on subject response. We found that 21% of paper questionnaires had at least one missing or uninterpretable item, with less than 3% of items missing overall. Other researchers have reported 5–10% of missing items on self-administered paper questionnaires16
and an increasing proportion of missing items with increasing questionnaire length.17
Because subjects were not allowed to skip items on the WBQ, this format eliminated the problem of missing data for this mode of administration. With an electronic questionnaire, the problem of missing data can be eliminated if the electronic format either does not permit subjects to skip individual items or if skipped items are presented a second time at questionnaire completion.8
For research on sensitive topics, participants should be given an option to “decline” any specific item if skipped items are not allowed by the questionnaire format.
We speculated that age, education and computer experience might impact questionnaire results, but we were not able to identify any significant differences in scores or subscale scores. The relatively high level of educational attainment in this population may have limited our power to detect differences. However, other researchers have found similar results. Specifically, age, level of formal education, and familiarity with computers do not seem to significantly influence the accuracy of electronic questionnaire results.8, 11, 13
A limitation of our research is the sample size. This may have limited the power of this study to detect differences in some of the scores considered. Also, the women who agreed to participate in this research may not reflect the population of women typically presenting for clinical care. Nevertheless, they are likely to reflect populations that participate in research and therefore we believe our results are generalizable to subjects enrolled in clinical research. Finally, the interval between completion of the first and second versions of the questionnaire may have been up to 6 weeks. It’s possible that symptoms may have changed over time. However, since the PFDI-20 and PFIQ-7 both specifically address symptoms “over the last 3 months”,5
we don’t believe an interval of 6 weeks would have a substantial impact on participants’ responses.
Approximately one-third of potential participants declined to join this study. We speculate that some of the women may have declined because of a lack of familiarity with computers or the internet. Indeed, the enrolled population was highly educated and familiar with computers. These observations suggest that researchers who plan to use a WBQ for data collection should plan an alternative mode of administration to facilitate participation by a broad cross-section of eligible women. Our data suggest that paper and WBQ versions of the PFDI-20 and PFIQ-7 can be used interchangeably in this situation.