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Re: st: repeated measures


From   Michael McCulloch <mm@pinestreetfoundation.org>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: repeated measures
Date   Tue, 7 Sep 2010 13:21:19 -0700

Thanks Nick, you're correct I did misread that part.
Nevertheless, I suspect that some of the complexity you allude to your your prior reply to Michael E. is that he wishes to selectively carry forward certain field values. For example, something like: replace the missing value from (first visit at which it's available ) if that value is present in that patient's first visit I would know how to define the first visit a patient had, but not how to find the first visit at which a lab value appeared.
Michael

On Sep 7, 2010, at 1:12 PM, Nick Cox wrote:

I think Michael M. is misreading this. It's a long to long mapping, so -reshape- does not spring to mind here. See my earlier suggestions.

Nick
n.j.cox@durham.ac.uk

Michael McCulloch

This is possible with the -reshape- command. What you are starting
with is the "long" data format, and you can use that command to change
to "wide." However, there appear to be a few problems with your
description:
1. Did you mean patient ID=4, not =3, in the last line of the data
format you're seeking?
2. In the desired data format you list the "glu" data point for
subject ID=3 as being from a different date than the original 6/1/09.

On Sep 7, 2010, at 12:54 PM, Michael Eisenberg wrote:

I have a problem I hope you can help with that involves cleaning a
dataset for analysis.

I have a dataset with about 10K men.  Several men had multiple clinic
visits, so that there are about 12K observations.  There is also some
lab data that I'll need that was not obtained until follow up visits.

I would like to only analyze data from the earliest visit and the
first available lab data.

Can stata do this?


Turn this

patient     visitdate    sbp       dm          glu
1              1/1/09       140       .             .
1              1/4/09       128       .            202
1              2/1/09       131      1            .

2              4/1/09       160      .             341
2              4/4/09       144       .            180
2              5/1/09       170      1            .

3              6/1/09       119       .             .
3              6/4/09       107       .            .
3              7/1/09       124      .            96

4              9/1/09       104       1          110
4              9/4/09       155       .            .
4             10/1/09       .         .              .

Into this

patient     visitdate    sbp       dm          glu
1              1/1/09       140      1             202
2              4/1/09       160      1            341
3              6/1/09       119       .            96
3              9/1/09       104      1            110


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Best wishes,

Michael McCulloch, LAc MPH PhD
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel:	415-407-1357
fax: 	206-338-2391

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