Dear Geoff,
thanks for explaining the problem.
The problem is not related to the selection of observations to be
included in the analysis (`touse' and `if' work as intended).
The problem is to keep the actual order of the selected observations
within each study when pooling multiple studies. I modified one line
of the -glst- command to address this point.
I will post a revised ado file on both SSC and SJ archives.
In the meantime, -sort- the dataset before running -glst- command with
multiple studies
or as alternative use the option tstage() which is not affected by -
sort-.
* Solution 1
sort study_id , stable
glst ln_rr_m dosage if collecc==1, ///
se(se_glst) cov(person_y case) pfirst(study_id study_e)
* Solution 2
glst ln_rr_m dosage if collecc==1, ///
se(se_glst) cov(person_y case) pfirst(study_id study_e) ts(f)
Nicola
On May 7, 2009, at 5:19 PM, G Livesey wrote:
Dear Nicola and Statalisters,
I am getting different estimates each time I run a glst command on
the same
dataset in Stata and would be glad of suggestions of how to resolve
the
problem.
The glst command is used here to estimate the dose-dependency of
effect in
observational or relative risk data.
The command and syntax, and extract from a dataset in use are shown
below.
I am using Stata v9.2, an up-to-date version of glst and the log data
(ln_rr_m and corresponding errors se_glst) were obtained with gen
double.
I would very much appreciate help with this crucial problem.
With thanks,
Geoff. Livesey
COMMAND AND SYNTAX:
glst ln_rr_m dosage if collect_c==1, se(se_glst) cov(person_y case)
pfirst(study_id studyexpression) random
DATA:
ln_rr_m dosage collec~c se_glst person_y case study_id study_e
0 0 1 0 39637 281 3 2
-.0725707 1.330824 1 .09000712 40218 265 3 2
-.1278334 2.439844 1 .09273151 40621 241 3 2
-.2613648 4.103374 1 .09935509 40956 198 3 2
-.4462871 7.430433 1 .10182739 41222 156 3 2
0 0 1 0 145258 219 7 2
-.1625189 1.212121 1 .10710753 141933 162 7 2
-.1392621 2.203856 1 .11429413 139945 151 7 2
-.198451 3.636364 1 .11990109 146011 132 7 2
-.4462871 7.493112 1 .14876455 143153 77 7 2
0 0 1 0 34750 204 8 2
-.1508229 2.187076 1 .10585496 35154 164 8 2
-.0618754 3.827383 1 .10787362 35196 172 8 2
-.1625189 5.649946 1 .11324987 35488 156 8 2
-.328504 9.112817 1 .12940233 35529 148 8 2
0 0 1 0 23988 456 9 2
-.0943106 1.14482 1 .07583086 25050 381 9 2
-.1165338 2.289639 1 .08001615 24227 357 9 2
-.1863296 3.663423 1 .03711996 26115 386 9 2
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