An investigation into the effect of questionnaire identification numbers in consumer mail surveys

This article deals with the effects of a somewhat overlooked response inducing technique in mail surveys, i.e. the inclusion of questionnaire identification numbers. Results indicate that the inclusion of such numbers has a positive effect on response rate and has no effect on item omission. Furthermore, it is suggested that efforts to make identification numbers more visible do not always produce desirable results. More specifically, it has been found that use of an inappropriate colour and excessive use of graphics have a negative effect on response rate.