Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

RE: st: Statistical advice about multiple comparison...


From   jverkuilen <jverkuilen@gc.cuny.edu>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Statistical advice about multiple comparison...
Date   Fri, 25 Jul 2008 18:52:21 -0400

Nonparametric tests tend to lose a lot of power when you have many ties as you will have here. 

You may benefit from a model for discete ordinal data such as -ologit-. However it is not set up for repeated measures analysis. You may find -gllamm- helpful there. See http://gllamm.org. 

-----Original Message-----
From: "Yupa" <lrdyupa@gmail.com>
To: "Statalist" <statalist@hsphsun2.harvard.edu>
Sent: 7/25/2008 6:04 PM
Subject: st: Statistical advice about multiple comparison...

Dear statalisters,

I have 9 test items and each item is scored ordinally 1 to 4 points 
(distance between points isn't equal).
The test is administered to two populations; in the first population 
each item is taken two times for each subject (at different ages). The 
second population served as reference.
Some of the test items show a ceiling effect (aren't able to 
discriminate at high end of the scale, and lower scores are not 
represented).
I have to compare the results of each item between the two timepoints of 
the first population and between each timepoint of the first population 
versus the reference population.
I think that an equality test for matched data is adequate for the first 
comparison (signrank) and an equality test for unmatched data (ranksum) 
for the second. 
Am I right or am I missing something?
May I analyze the data in a different way (different tests)?

Thanks in advance!
Francesco
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index