Re: Sample size - How big should it be?

- taking one digression here -

On Mon, 28 Jan 2008 06:00:49 GMT, Rob <user@xxxxxxxxxxx> wrote:

[snip, much]

Side question here - When dealing in surveys aren't the samples always
to some extent, self selected anyway?

Not every one is going to respond to a survey. You can't force them and
if you could they might give false information just to get rid of you.
[snip, rest

"Self-selected", sure, if you are talking only about the type
of survey that uses one phone call. By the way, I think that
good political pollers do make more than *one* attempt to
reach a number. And they should keep track of which attempt
succeeded, in case "hard to reach" makes a difference in outcome.

Similarly, there are surveys that use mail for contact. Or
follow up phone calls with mail, etc. - If the "quick responders"
look just like the "slow responders", the pollster will be happier.

The U.S. government publishes surveys of employers, and surveys
of markets, though this is the sort of knowledge-seeking that the
Bush Administration has worked to de-fund. (Republican tax and
economic policies sell better with ignorance.)

--
Rich Ulrich
http://www.pitt.edu/~wpilib/index.html
.

Relevant Pages