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Re: st: Survival Analysis

From   Steve Samuels <>
Subject   Re: st: Survival Analysis
Date   Mon, 17 Jun 2013 22:07:18 -0400

The time frame of a retrospective review (your 1994 to 2012) is irrelevant to the survival analysis setup, which formally needs a start date, end date, failure indicator, and covariates.

The definition of a survival cohort usually begins with a range of start dates; an example :"all patients presenting at so-and-so clinic with a diagnosis of such-and-such, from dates A through Z, followed to death or to date W").
You may restrict to those whose records received the special review, but the important question is: what determined which records were reviewed?  Unless the reviewed records were  100% or, effectively, a random sample of those eligible, you risk selection bias. So more information on the definition of your cohort would be helpful. 

I am curious about where you are doing this work, as an internet search finds no links to your name except for two Statalist posts this month.


On Jun 10, 2013, at 10:00 AM, Reese Andorfer wrote:

Dear All,

I will perform a Cox Regression and I am currently preparing my data;
The time span I'm looking at is from 1994 to 2012, individuals
accounted for which received a special examination within this time
So, it is know possible that an individual died before 1994 (let's say
starting in 1979 and died in 1986) , but I still have it as an
observation since it's case got reviewed in 1994 or later; and I
actually only care for its survival time and the associated
covariates, however I was wondering now if it would suffice that I
create a variable that indicates the year when the individual "died"
or would you recommend incorporating sth. else.

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