Effects of two telephone survey methods on the level of reported risk behaviours

Reporting bias due to social desirability is an important consideration in carrying out surveys on sensitive issues. The study compared the frequency of self reported sensitive behaviours and response rates between the conventional "telephone interviewer method" (TIM) and a combined interviewer and computerised data capturing method (telephone interviewer and computerised questionnaire method, or TICQM).

A total of 580 males and 582 females were recruited and randomly assigned to either of the two methods in a cross sectional study. The overall response rate was about 51.6%.

While the two methods both had high completion and low item non-response rates, the TICQM respondents reported higher frequencies of sensitive risk behaviours. Sexually active female respondents interviewed by the TICQM were more likely to report that their sex partners were their steady boyfriend, instead of their husband; and were also more likely to admit that they had had "one night stand" experiences or had undergone an HIV antibody test, when compared with their counterparts in the TIM group. Similar contrasts were observed for sexually active male respondents, that the TICQM group were more likely to report that they had had sexual intercourse with female sex workers or non-regular sex partners. Sex differences in the strength of association were observed between some studied behaviours (for example, HIV testing and substance abuse) and modes of data collection.

The choice of data collection method has a significant impact on the results of sensitive studies; special attention should be given to designing the study and interpreting the results.