Our paper of the year today has been selected by Dr Gozde Ozakinci, Scottish Cancer Foundation Board member from University of St Andrews.

Questionnaire surveys provide guidance for action and understanding – but should we think again ?

Ellis, E. M., et al. (2018). “Relationship of “don’t know” responses to cancer knowledge and belief questions with colorectal cancer screening behavior.” Health Psychol 37(4): 394-398.


It’s important that we understand what ‘don’t know’ responses in cancer surveys means as we use the findings in prevention support programme development. For instance, ‘don’t know’ is a common response to risk perception items occurring more frequently among individuals of low socioeconomic status, low educational attainment, minority race/ethnicity, and low health literacy/numeracy.

In this study, the authors examined the ‘don’t know’ responses to ‘cancer symptom knowledge’ and ‘cancer beliefs’ and their association with colorectal cancer screening. They found that ‘don’t know’ responses to ‘cancer symptom knowledge’ were not related to colorectal screening whereas responding ‘don’t know’ to ‘beliefs about cancer items’ were linked with lower odds of being screened. This suggests that ‘don’t know’ responding has consequences depending on whether they rely on knowledge or belief mechanisms. It’s important that researchers carefully consider what they do with these responses and considering them missing data or lumping them with other responses may misrepresent responses from underrepresented populations already at risk for adverse health outcomes. This article provides much food for thought for cancer prevention researchers who often rely on survey findings.