# st: RE: repeated sampling of emergency department patients

 From austin nichols <[email protected]> To [email protected] Subject st: RE: repeated sampling of emergency department patients Date Fri, 8 Jul 2005 16:19:03 -0400

```If I understand you correctly:
You should regress Y on X1 and X2, and cluster by ED to allow for
arbitrary serial correlation. Include a time trend to allow the usage
of Y to change over time, and include a dummy for the quality
initiative started at month 7.  I hope it didn't start in every Dept
in month 7 (i.e. I hope you have some kind of control group).

#delimit;
g byte y=(MedicationY=="Yes");
g byte smoker=(Smoker=="Y");
g tm=ym(year(date(substr(var1,1,3)+" 15
"+substr(var1,4,2),"mdy",2060)),month(date(substr(var1,1,3)+" 15
"+substr(var1,4,2),"mdy",2060)));
format tm %tmYM;
qui su tm;
gen month=tm-r(min)+1;
probit y smoker age month qualinit, cluster(EmerDept);

If you have sampling weights, the problem is slightly different.

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Friday, July 08, 2005 3:36 PM
To: [email protected]
Subject: st: repeated sampling of emergency department patients

We have the following dataset:
Monthly survey of patients who report to an emergency department (across
15 months) and if they use medication Y  (y/n).  We also have other data
on the patients' characteristics (X1, X2, etc).

6 different hospital emergency departments were surveyed.  Each month we
targeted 15 patients, but sometimes less (or more) were enrolled.
ID          Emer Dept   Date    Smoker          Age     Medication Y
1               1       jan03   Y               10      Yes
2               1       jan03   N               45      No
3               2       feb03   Y               23      No

We are trying to assess whether:
1) Use of Y changes across time
2) If X1, X2 are predictors of use of Y
3) Use of Y is associated with a particular emergency department
4) A quality initiative started at month 7 makes a difference in the use
of Y

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```