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?
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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
*
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