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Hi<br>
<blockquote cite="mid:6.2.1.2.2.20090508133512.045f80b0@hawaii.edu"
type="cite">At 10:32 AM 5/8/2009, jimjohn wrote: <br>
<blockquote type="cite">does anyone here know how to compute
hypothesis tests/confidence intervals <br>
for the difference between two means in SPSS? For example, I am
comparing <br>
the volume growth of my certificates with balance less than $1000
versus the <br>
volume growth with balances greater than $1000. I want to see if the <br>
difference in the two means is statistically significant. Any ideas? I
don't <br>
think comparing means does it because it has something about grouping
and <br>
factors. thanks! <br>
-- <br>
</blockquote>
</blockquote>
IF I understand your question correctly, "balances" is not categorical,
but quantitative too. the t test can be used, without having to
dichotomize balances.<br>
<br>
See this example, using the General Survey data that comes with SPSS.
Suppose we want to compare number of children between those who have
less than 12 years of education vs those who have 12 or more years.
Instead of defining two groups, just use the cut-off:<br>
<br>
GET FILE='U.S. General Social Survey.sav'.<br>
<br>
T-TEST<br>
GROUPS = educ(12)<br>
/VARIABLES = childs.<br>
<br>
Anyway, I also agree with ViAnn: you are throwing away a lot
ofinformation. See "Altman DG, Royston P. (2006) <a
href="http://bmj.bmjjournals.com/cgi/content/full/332/7549/1080">
The cost of dichotomising continuous variables.</a>
<b>332</b>, 1080.
"<br>
<br>
HTH,<br>
Marta<br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
For miscellaneous SPSS related statistical stuff, visit:
<a class="moz-txt-link-freetext" href="http://gjyp.nl/marta/">http://gjyp.nl/marta/</a></pre>
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