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st: RE: set: expanding data set by variable

From   "George Gunapal Pradeep Paul (NHGHQ)" <>
To   "" <>
Subject   st: RE: set: expanding data set by variable
Date   Wed, 9 May 2012 04:59:48 +0000

Hi all,
I am have data on Chronic obstructive pulmonary disease patients who were enrolled in a disease management program and a group of controls. I used psmatch2 to match program patients  and controls patients using a set of covariates. Now I would like to compare the matched cases and controls using the command (matched case control) and also would like to run a cox regression on the matched cases. The MCC option asks me to select the matched cases and controls. Am I missing out on any variables generated after psmatch2 which can identify the matches case and controls? Look forward to your help.

Thank you,

-----Original Message-----
From: [] On Behalf Of KOTa
Sent: Wednesday, May 09, 2012 8:19 AM
Subject: Re: st: expanding data set by variable

thanks for quick response, Nick

> 1. What the date variables are (string, numeric, numeric with a date format)?

sorry i just didnt think to mention this, cause it can easily converted among those formats you listed. ( and i actually have dates in all 3 of them)

> 2. Why you think the second data structure is going to be a good one?

what i am trying to do is to count the time spent on each "type" of activity. which i already figured out how to do (with the help from the statalist ) but the problem is if activities overlap in days for same person and i dont take account for this - i over-count them both.
so what i tried to do is to split time equally among requests (ID) that happened at the same time(for same user). i managed to do this for requests (ID) that start at the same time, but could not find a way to do this if they start at different times (and it can be overlap between more then 2 requests). the aprouch i though to take is to recode the data so each observation would be split into not overlapping periods.

> If this were my data, I would get a different structure this way:
> ...
> gen mydate = date(string(start, "%12.0f"), "YMD") gen mydate2 =
> date(string(end, "%12.0f"), "YMD") format mydate %td gen length =
> mydate2 - mydate + 1

that is how i started

> expand length

that what i wanted to do, but could not find in the help or examples if "expand" can be used this way

> bysort ID : replace mydate = mydate + _n - 1

1. i forgot to mention that the count has to be by activity type. so, correct me if i wrong the bysort then should be "bysort ID type" ..."
2. i didn't understand the logic of replace mydate = mydate + _n - 1

thanks again
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