Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: Cutpoints and Data


From   Marcello Pagano <pagano@hsph.harvard.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Cutpoints and Data
Date   Sun, 30 Nov 2003 20:49:40 -0500

Once you have decided on the cutpoints, here is an old listing from 1997 that gives
a few references to help you get the theory right:

m.p.
_______________________________________________________________________________

Here are some that I know about. I'd also appreciate other references.


Altman, D.G., Lausen, B., Sauerbrei, W., and Schumacher, M.
Dangers of using "optimal" cutpoints in the evaluation of prognostic factors. Journal of the National Cancer institute 86(11):829-835, 1994.
Hilsenbeck, S.G. and Clark, G.,M. Practical p-value adjustment for optimally selected cutpoints. Statistics in Medicine 15:103-112, 1996.

Kornblau, S.M., Thall, P.F., Huh, Y.O., Estey, E., and Andreeff, M.
Analysis of CD7 expression in acute myelogenous leukemia: martingale residual plots combined with 'optimal' cutpoint analysis reveals absence of prognostic significance. Leukemia 9:1735-1741, 1995.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Judith Abrams jabrams1@biostat.hfh.edu
Biostatistics & Research Epidemiology
Henry Ford Health Sciences Center
1 Ford Place/3E
Detroit, MI 48202-3450
Ph (313) 874-6408 Fax (313) 874-6730

_________________________________________________________________________________

Allen Buxton wrote:


You might try checking the command "egen"

egen group_varA = cut(varA) , group(x) label

this will group varA into x groups with approx. the
same frequency. Is this what you wish to do?

-Allen Buxton


--- tpolcyn <tpolcyn@dal.ca> wrote:


Hello,
After many unfruitful hours perusing STATA manuals
and the Archives, I thought it might be best to query the knowledgeable group on
the listserve.

One of my independent variables for my panel dataset
ranges from a scale of 1 to 7. My professor therefore suggested that I
investigate ologit and oprobit models for my regressions. Unfortunately, my
dependent variables are uncooperative in this respect because they all have
a range of more than 50 categories.

I have looked at a kdensity of my dependent
variables and used the tabulate command for assistance in determining where to
impose cut points. I am aware of "hordered" which performs a Hausman-type
specification test whether categories in a ologit or oprobit model can be
joined or dropped. To this end it estimates another ologit/oprobit model with a
collaped response.

My question though is how do I go about grouping my
data? How do I divide my data into for example three ordered groups? I think
I am missing some basic STATA manipulation....

Many thanks,
Tania Polcyn

Master's of Development Economics
Dalhousie University
Halifax, Canada

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   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