Re: st: date of last follow up

[Richard Goldstein <richgold@ix.netcom.com>]

if visitdate is a Stata date (see -h dates-), then just go

egen maxvstdate = max(visitdate), by(subjectid)

if visitdate is not a Stata date (e.g., it is a string), then make into
a Stata date (-h dates-)

Rich

On 9/13/11 12:33 AM, Michael Eisenberg wrote:
> Colleagues,
> 
> I'd like some help working with dates in Stata.
> 
> I have a list of visits for several patients.  I'd like to make a
> column which lists the date they were last seen.  In other words, a
> date of last follow up.
> 
> I'm fairly certain I need to start with a bysort command, but I'm not
> sure what should come next.
> 
> My data looks as follows.
> 
> subjectid   test      visitdate
> 1                r            1-3-2010
> 1                q            2-1-2009
> 1                e            6-3-2011
> 2                q            2-1-2006
> 2                e            6-3-2008
> 3               r              1-3-2005
> 4                q            2-26-2009
> 4                e            6-13-2011
> 4                r             10-23-2010
> 2                q            2-15-2007
> 1                e            6-30-2004
> 
> Thank you in advance.
> 
> Mike
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