<html> <body> At 02:42 PM 8/1/2003 -0400, you wrote: <blockquote type=cite class=cite cite>Jon Johanning wrote: <blockquote type=cite class=cite cite>I'm not an expert in the science (?) of polling, but I think I've seen several stories recently noting that pollers are getting increasingly frustrated trying to find valid samples, given that they get a lot of answering machines when they try to call folks, or when they do reach them, folks refuse to participate, etc.</blockquote> Yup, the refusal rate is up, people are switching from land lines to cell phones (which aren't as easily accessible), caller ID means people aren't answering the phone, etc. Accuracy doesn't seem to have suffered all that much, though. </blockquote> I know a little about polling and telephone surveys, having conducted a few myself over the years, and I'm also affiliated with a research shop that does them by the bucket-load.  Things have gotten pretty awful over the last 20 years, the last 5 in particular.   For a while Random Digit Dialing (RDD) got past the problem of unlisted numbers (but not the problem of pissing off the people with the unlisted numbers that you got), but increasingly people are opting out of the sampling frame altogether by going cell phone only.  I, in fact, am one of them.  Once cable Internet was available to me about a 2 years ago I bailed on ATT.  So now there's no way I get included in anyone's telephone sample.  It's a gradual return to the 1940s when (for better or worse) it all got started.  You all recall the picture of Truman holding up the newspaper headline that says "Dewey Beats Truman."  That headline was based on polling that didn't include the democrats who didn't have phones but were able to vote.  Your sample is only as good as your sampling frame. In grad school I worked for a while under Don Dillman, who wrote the bible on telephone and mail surveys (The Total Design Method for Mail and Telephone Surveys-- or TDM-- or TEDIUM, as we liked to refer to it).  He has a new edition of it out in which he discusses some of these issues and is likely to be on top of any research trying to overcome such problems (A Sociological Abstracts search will find the latest stuff).  Don is nothing if not persistent. I did my last phone survey about 5 years ago and wouldn't trust one today-- at least if one is using a phone survey as a proxy for a household survey.  If I had to do a household survey today it would be back to pounding the pavement door to door with multiple return visits to get the "not home" folks.  If money was an issue, I'd take a smaller sample size, with tractable margins of error, versus the utterly unknown (and probably unknowable) error between the population and the sampling frame resulting from using telephone surveys today. Cliff </body> </html>