Despite years of refinement and improvement to questionnaire design, the need remains to identify effective, but 'user-friendly' questioning procedures to predict behaviour, without compromising predictive performance. Questionnaires developed to predict behaviour typically use an attitudinal approach. However, those types of questionnaires are associated with increased respondent fatigue, decreased question comprehension, opposition to question tone and demand effects. An alternative approach involves use of factual questions. This study compares ease of application in the field as well as predictive performance of the two approaches to questionnaire design in the context of predicting willingness to donate blood. Results indicate that factual questions are quicker and easier to apply in the field than attitudinal questions, while predictive performance of the approaches is equivalent.