RE: Re: st: RE: Patient age at first cancer exam in STATA

[Joe Canner <jcanner1@jhmi.edu>]

Actually, I'm sure there are cancer patients in there, but Cancer==0 because the first record for each patient is a 0. You can solve this in one of two ways:

1. Create a variable (before the collapse) that indicates if the patient had any records with Cancer==1

bysort Patid: egen anyCancer=max(Cancer)

(Come to think of it that count variable we created before can also help; it's a cancer patient if the count is greater than 0)

2.Sort the records by Patid and Cancer and take the last one instead of the first one.

bysort Patid (Cancer): keep if _n==_N

________________________________________
From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] on behalf of mafotb@gmail.com [mafotb@gmail.com]
Sent: Saturday, January 11, 2014 10:03 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: Re: st: RE: Patient age at first cancer exam in STATA

Dear Joe,

I have tried both: bysort Patid: keep if _n==1 and collapse.

Unfortunately none of them did work. It only kept 377 unique Patid,
neither of them was a cancer patient.

KR
John
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