Validity estimates such as concordance, sensitivity, and specificity provide useful information on the agreement between self-report and medical records, but they tell us little about factors that influence accuracy. We found that although several factors were associated with social desirability scores, social desirability was not associated with concordance for any of the CRC screening tests. Our findings were similar to those of Matthews and colleagues (11
) who found that although social desirability was associated with race ethnicity, it was not associated with the accuracy of self-reported CRC screening. These findings are consistent with the view that overreporting of CRC screening may not be attributable to a tendency among survey respondents to present themselves in a favorable manner relative to perceived social norms.
Although social desirability was not measured directly, 2 studies evaluated strategies to reduce the influence of social desirability on self-reported cancer screening behaviors (10
). Although not statistically significant, Johnson and colleagues (12
) found self-reports of mammography and Pap testing were more accurate (i.e., in agreement with medical records) when an intention question preceded questions about screening. Beebe and colleagues (10
) also examined the effect of social desirability on self-reported CRC screening by asking a question about intention to get screened before or after asking about past screening behavior. They found that asking about intention before asking about screening resulted in lower reports of screening; however, self-reports were not validated against medical records. These findings indirectly support the view that social desirability influences responses to questions about cancer screening behaviors.
Although social desirability was not associated with the accuracy of self-reported CRC screening in our study, it is notable that higher social desirability scores were observed for some subgroups. Telephone survey respondents compared with mail or face-to-face respondents reported higher social desirability scores, suggesting that different modes of data collection may create different demand characteristics among respondents, a finding that deserves further investigation in future studies, particularly as new communication technologies, such as the Internet and smart phones, are used to collect survey data.
Limitations of our study are that the results may not generalize to other populations because study participants were a self-selected sample of relatively educated patients from one medical practice in a large urban area. Given our findings of subgroup differences in social desirability scores by race and education in this relatively homogeneously population, future studies should examine the effect of social desirability on the accuracy of self-reported CRC and other screening behaviors in more diverse populations. Despite general agreement that social desirability may influence the accuracy of self-reports, there is no consensus about how to measure it. Future studies should explore alternative ways to measure this construct. Nevertheless, social desirability, as measured by the Marlowe–Crowne scale, was not associated with accuracy of self-reported CRC tests in our sample, suggesting that other explanations for overreporting need to be explored. For example, telescoping, a cognitive memory error that occurs when an event is recalled as occurring more recently or more distally than it did in fact occur, also may lead to overreporting (20
Our findings extend prior research by measuring social desirability using a validated scale and by assessing its association with sociodemographic and other variables and with the accuracy of self-reported CRC screening behaviors. Our findings also provide support for the use of survey measures, such as the one used in this study, to monitor the prevalence of screening and to evaluate intervention effects when medical records are unavailable.