Statalist The Stata Listserver


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

Re: st: specify groups within a group


From   "Alan Neustadtl" <[email protected]>
To   [email protected]
Subject   Re: st: specify groups within a group
Date   Fri, 8 Dec 2006 07:27:52 -0500

You can also use bysort: for somethings as shown below, or you can
(e)gnerate a new variable for each combination of the values of your
two variables and use these values in a loop or if statement.

sysuse auto, clear
bysort foreign rep78: sum mpg

egen cmbgrp=group(foreign rep78)

Best,
Alan

On 12/8/06, Joseph Coveney <[email protected]> wrote:
Lucy Shum wrote:

Hi all, could anybody advise on how to specify in STATA, analysis of
specific groups within a category? That is, if I have a category called
events_mastitis - there are 7 different groups meaning there are animals
that experienced between 1 - 7 episodes of mastitis within a lactation. Say
if I only want STATA to analyze, tabulate, create graphs of.., say Group 1
and 5 only. How do I go about doing that?

Also, using the example above, how do I go about writing a command so that
STATA compares the survival estimates of these 7 groups? Logrank? Is there a
modified procedure that deals with comparison of greater than 2 groups?

--------------------------------------------------------------------------------

You can use -inlist()- to select groups:

tabulate pathogen if inlist(events_mastitis, 1, 5)

You can use Stata's survival commands for comparing more than two groups.
The example below creates four groups (age categories) and peforms a
log-rank test and Cox regression.

Joseph Coveney

use http://www.stata-press.com/data/r9/catheter, clear
bysort patient (time): keep if _n == _N
egen byte age_category = cut(age), group(4)
stset time, failure(infect)
sts test age_category
xi: stcox i.age_category
exit


*
*   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/

*
*   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 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index