[EpiData-list] (no subject)

epidata-list at lists.umanitoba.ca epidata-list at lists.umanitoba.ca
Mon Sep 29 10:36:11 CDT 2014

In Epidata Analysis, do this:
(I’m using id and visit - you cannot have names with underscores in classic Epidata and it is probably not a good idea in new Epidata)

define vfirst #
vfirst = 1
sort id visit
if id = id[recnumber-1] then vfirst = 0
select vfirst=1

id[recnumber-1] refers to the value of id in the previous record. Since the data are sorted first by id and then visit, this will leave vfirst=1 whenever id changes.


On Sep 29, 2014, at 8:41 AM, epidata-list at lists.umanitoba.ca wrote:

> Dear ALL,
> I have a data set where some patients have more than one entry (visit) i.e.
> same patient with different visit dates, while some have only one entry
> (visit). I would like to select only the first visit from each patient (The
> variables to use are  id_unique and visit_date)
> Regards
> Walter
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> EpiData-list mailing list
> EpiData-list at lists.umanitoba.ca
> http://lists.umanitoba.ca/mailman/listinfo/epidata-list

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