Testing the Question Behaviour Effect Hypothesis Versus the Non-reponse Bias Hypothesis

Abstract

Introduction We study whether previous findings in studies on blood donation behaviour that were labelled question behaviour effect (QBE) could actually reflect a non-response bias (NRB) instead. Higher response rates have also been associated with finding QBE. Methods Blood donors (N=1,395) were randomly allocated to one of six experimental questionnaire conditions or to a control group. The questionnaire conditions either included intention items to trigger a QBE, general health items, both items, and handwritten post-its to increase response rate or not. The outcome variable was the % of donors that donated after receiving a standard invitation. Results The questionnaire conditions did not influence the odds of donation compared to the control group (OR’s ranged from 0.70 to 1.01). Non-responders showed significantly lower odds of donating than controls (ORresponders: 1.05, 95%CI: .77-1.45; ORnon-responders: .63, 95%CI: .45-.88). Discussion Regardless of the content or response rate, receiving or filling in questionnaires does not seem to increase blood donation. However, non-responders donate less than responders. These findings support the NRB hypothesis over the QBE hypothesis.