Russel-Research-Method-in-Anthropology

280 Chapter 10
which means that
P (the true proportion) 1.96PQ / n Formula 10.1
1.96(.70)(.30)/10 .28
The probable answer for the 10 holdouts is .70.28. Somewhere between
42% and 98% of the 98 nonresponders from the 1989–1990 cohort probably
had nonacademic jobs. We guess that between 41 and 96 of those 98 nonresponders
had nonacademic jobs. We can now make a reasonable guess: 123 of
the responders plus anywhere from 41 to 96 of the nonresponders had nonacademic
jobs, which means that between 164 and 216 of the 306 people in the
cohort, or 54% to 71%, probably had nonacademic jobs.
Low response rate can be a disaster. People who are quick to fill out and
return mailed questionnaires tend to have higher incomes and consequently
tend to be more educated than people who respond later. Any dependent variables
that covary with income and education, then, will be seriously distorted
if you get back only 50% of your questionnaires. And what’s worse, there is
no accurate way to measure nonresponse bias. With a lot of nonresponse, all
you know is that you’ve got bias but you don’t know how to take it into
account.
Improving Response Rates: Dillman’s Total Design Method
Fortunately, a lot of research has been done on increasing response rates
to mailed questionnaires. Yammarino et al. (1991) reviewed 184 controlled
experiments, done between 1940 and 1988, on maximizing the return of
mailed questionnaires, and Don Dillman, of the Survey Research Laboratory
at Washington State University, has synthesized the research on maximizing
return rates and has developed what he calls the ‘‘Total Design Method’’
(TDM) of mail and telephone surveying (Dillman 1978, 1983; Salant and Dillman
1994).
Professional surveys done in the United States, following Dillman’s method
achieve an average return rate of around 73%, with many surveys reaching
an 85%–90% response rate. In Canada and Europe, around 79% of personal
interviews are completed, and the response rate for mailed questionnaires is
around 75% (Dillman 1978, 1983). Of course, those numbers are for the usual
kinds of surveys about consumer behaviors, political attitudes, and so on.
What happens when you ask people really threatening questions? In the Neth-