A total of 274 (54.8%) questionnaires contained sufficient data for use in the
analysis. Reluctance to reveal financial information may account for the low
response rate despite use of multiple follow-up procedures. Based on a
review of the literature on non-response bias DeMaris and Jackson (1986, p.461) concluded that in studies on topics such as this, "nonrespondents and respondents tend to be demographically
similar, and nonresponse bias maybe expected to pose little threat to the substantive conclusions.