On Thu, 20 Apr 2000 terry <[EMAIL PROTECTED]> wrote:
> I am somewhat green when it comes to stats and these may be basic
> questions but here goes.
> I am trying to determine the correct sample size for a 1 sample t.
> The population is 8,000 and I realize the n>=30 rule,
> but what if this is descriptive stats
> with only two possibilites (y/n answer)
> Am I using the wrong tool?
You need a few more constraints than you have described. By "1 sample t"
do you mean that you want to test a null hypothesis using a t-test, or
that you want a confidence interval based on the t distribution?
You describe your observed variable as dichotomous, which implies that
you're trying to estimate a proportion. If you're testing a hypothesis,
what is the value of the population proportion specified by the
hypothesis? And what minimum distance from that value do you want to be
able to distinguish, with what probability? Equivalently, if you're
interested in a confidence interval, how narrow do you want the interval
to be, with what degree of confidence (often expressed as a %, like 95%)?
You write, "what if this is descriptive stats". If this is the case, why
are you dealing with t at all? Ordinarily one invokes the t
distribution (either as a t-test or as the basis for a confidence
interval) when one is trying to infer something about a population (your
8,000, I take it), not if the enterprise is only descriptive.
You mention a "n >= 30 rule". What, precisely, do you understand by
that phrase? (One can imagine a variety of "rules" that might be so
described, most of them rather idiosyncratic. It is not clear that any
of them would actually apply in your situation; although it is quite
possible that some folks would insist on one or another.)
------------------------------------------------------------------------
Donald F. Burrill [EMAIL PROTECTED]
348 Hyde Hall, Plymouth State College, [EMAIL PROTECTED]
MSC #29, Plymouth, NH 03264 603-535-2597
184 Nashua Road, Bedford, NH 03110 603-471-7128
===========================================================================
This list is open to everyone. Occasionally, less thoughtful
people send inappropriate messages. Please DO NOT COMPLAIN TO
THE POSTMASTER about these messages because the postmaster has no
way of controlling them, and excessive complaints will result in
termination of the list.
For information about this list, including information about the
problem of inappropriate messages and information about how to
unsubscribe, please see the web page at
http://jse.stat.ncsu.edu/
===========================================================================
