Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: calculating cumulative exposure


From   Raoul C Reulen <r.c.reulen@bham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: calculating cumulative exposure
Date   Fri, 3 Aug 2007 15:36:48 +0100

Dear statalisters,

I‘ve got multiple records per person and want to calculate some kind of cumulative exposure index per person. I’ve got a variable called “exposure” and want to create a new variable called “cum_exposure”. Each observation in the cum_exposure variable should give the sum of all previous cells in the exposure column (but per person). So something like this: 

Id	Exposure	list		Cum.Exposure
1	10		1			10
1	14		2			24
1	15		3			39
2	8		1			8
2	10		2			18
2	15		3			32

I’ve tried this:

.by id: gen list=_n 
.gen cum_exposure=.
.replace cum_exposure= exposure[1]  if list==1
.replace cum_exposure= exposure[1] + exposure [2]  if list==2
.replace cum_exposure= exposure[1] + exposure [2] + exposure[3]  if list==3

But how can I do this more efficiently? In a loop for example?


Thanks, 

Raoul

Raoul Reulen
Cancer Research UK Graduate Training Fellow
Centre for Childhood Cancer Survivor Studies
Department of Public Health & Epidemiology
University of Birmingham
Birmingham
B15 2TT
tel.: +44 (0)121 414 4946
fax.: +44 (0)121 414 7923
email: r.c.reulen@bham.ac.uk
website: www.bccss.bham.ac.uk


*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index