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RE: st: count number of cases rather than observations


From   "David Winter" <d.l.winter@bham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: count number of cases rather than observations
Date   Mon, 28 Nov 2005 17:23:29 -0000

Thanks Eric - this was very helpful

***********************************************************
Mr David L. Winter, HNC
IT Manager (BCCSS Study)
Department of Public Health & Epidemiology
University of Birmingham
Edgbaston
Birmingham
B15 2TT
UK
tel: +44 (0)121 4146766
fax: +44 (0)121 4147923
***********************************************************


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Eric Cahuzac
Sent: 25 November 2005 08:30
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: count number of cases rather than observations


David,
try in two steps:

preserve
bysort id-number riskint: keep if _n==1
bysort riskint: count
restore

the count instruction give
------------------------------------
-> riskint = 0-9
    5
------------------------------------
-> riskint = 10-19
    2

not so pretty but working...
Eric


David Winter a écrit :

>Hello,
>
>I have some survival data and I want to identify the number of cases
>that contribute person-time at risk. I also want to split the case by
>age. I -stset- and -stsplit by age (entry to exit) and the by risk
>interval:
>
>stset var1 enter(time var2) fail(censor-var) id(id-number)
>stsplit ageband at (.....)
>
>stset var3 enter(time var4) fail(censor-var) id(id-number)
>stsplit riskint at (....)
>
>for 5 cases I might have the data split as follows:
>
>id-number       ageband        riskint
>---------       -------        -------
>1               0-4            0-9
>1		    5-9		 0-9
>1               10-14          10-19
>2               0-4            0-9
>2               5-9            0-9
>3               0-4            0-9
>4               0-4            0-9
>5               0-4            0-9
>5               5-9            0-9
>5               10-14          10-19
>
>If I group by 'riskint' I would get the following result based on
>observations
>
>Riskint	no of obs (contribute person-time at risk)
>-------     ---------
>0-9             8
>10-19           2
>
>But what I want to identify and record is the no. of cases contributing
>person-time at risk in each risk interval.
>
>Riskint      no of cases
>-------      -----------
>0-9             5
>10-19           2
>
>There must be an easy way to do this?
>
>Best wishes,
>Dave             
>
>****************************************************
>Mr David L. Winter, HNC
>I.T. Manager (BCCSS Study)
>Department of Public Health & Epidemiology
>Room 105, Public Health Building
>University of Birmingham
>Edgbaston
>Birmingham
>B15 2TT
>UK
>tel.: +44 (0)121 414 6766
>fax.: +44 (0)121 414 7923
>****************************************************
>
>
>*
>*   For searches and help try:
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>*   http://www.ats.ucla.edu/stat/stata/
>
>
>  
>


-- 
______________________________

Eric Cahuzac
Institut National de la Recherche Agronomique (INRA)
Station d'Economie et Sociologie Rurale (ESR)
Chemin de Borde-Rouge - Auzeville
BP 52627, 31326 CASTANET-TOLOSAN CEDEX
Tel. 05.61.28.53.41 (direct)
     05.61.28.53.49 (secrétariat)
Fax. 05.61.28.53.72
e-mail  cahuzac@toulouse.inra.fr
http://www.toulouse.inra.fr/esr

*
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