Believe it or not! longer questionnaires have lower response rates

The effects of questionnaire length on response rate and response bias were examined by conducting a mail survey of 8534 persons taking distance education courses in insurance and financial planning. In 14 replications, persons were randomly assigned to receive a long or short course evaluation questionnaire. Response rate for the short form averaged about 28% higher than for the long form, and was significantly higher in all 14 replications. A measure of course satisfaction appearing on both questionnaires showed no significant differences between the long and short form in 12 of the 14 replications. The results suggested that biased measurement of consumer satisfaction does not necessarily occur on a long questionnaire with a relatively low response rate.