Factors Affecting Response to Mail Questionnaire : Research Topics, Questionnaire Length, and Non-response Bias

Abstract

To evaluate the feasibility of mail questionnaire for eidemiological studies in general population in Japan, we mailed six types of questionnaires which differed in lengths and topics to male residents drawn from a telephone directory of Gifu City in Japan. Those who were allotted to the shortest questionnaire and not responded after the initial mailing were assessed by followup processes with a second mail and a personal contact by telephone. We classified the subjects as early (on the first mailing) and late (on the second mailing) respondents, and nonrespondents (respondents to telephone interview), and compared histories of cigarette smoking and drinking, and environmental exposure to solvents among these three groups. The response rates after the first mailing ranged from 32-54% across the six types of questionnaires. Although somewhat lower response rates were noted for the longer questionnaires, there were no significant differences in the response rates by type of questionnaire. Although the second mailing increased the response rate to nearly 70%, there was a evidence of non-response bias. Cigarette smokers and drinkers were more likely to be the nonrespondents. J Epidemiol, 1995; 5 : 81-85.