Date: Thu, 18 Mar 2010 13:52:22 -0000
Reply-To: Garry Gelade <garry@business-analytic.co.uk>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Garry Gelade <garry@business-analytic.co.uk>
Subject: Re: non-parametric one-sample test?
In-Reply-To: <COL104-W324EFAAC3DFD2EB1E4CD30E92B0@phx.gbl>
Content-Type: multipart/alternative;
Dear Chris,
You might try a data transformation such as 1/x or log(x) to see if that
makes the distribution closer to normal, and then use a t-test. Or, f you
have the stomach for it, bootsrapping.
Garry Gelade
Business Analytic Ltd.
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Chris Smith
Sent: 18 March 2010 10:29
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: non-parametric one-sample test?
Hi
I have a data set of roughly 50 companies - each were asked to state the
percentage of their work that they would classify as 'green' in nature.
I want to run a test to show that over the sample, this differs from
50%, i.e. on average there is not an even balance between green and
non-green work being done.
If this was a normally distributed variable, I'd run a standard
one-sample t-test - however the distribution is fairly positively skewed
(most companies seem to report between 10-30% - a few report higher),
but with a small spike at 100%. Therefore at the very least trying a
non-paramtric equivalent alongside a t-test seems appropriate - however
going through the SPSS menus I can't find the non-parametric equivalent
to the one-sample t-test. Any ideas/refernces - I'm sure I'm missing
something obvious here!
Thanks in advance for any help
Chris
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