Key points are not available for this paper at this time.
Harold A. Edgerton, Steuart Henderson Britt, Ralph D. Norman, Objective Differences Among Various Types of Respondents to a Mailed Questionnaire, American Sociological Review, Vol. 12, No. 4 (Aug., 1947), pp. 435-444
Edgerton et al. (Fri,) studied this question.