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st: RE: Creating a variable from overlapping intervals

From   "Keith Dear" <>
To   <>
Subject   st: RE: Creating a variable from overlapping intervals
Date   Thu, 30 Dec 2010 16:15:24 +1100

Think about what is necessary for #2 NOT to be concurrent with #1:
either #2 must start after #1 finished, or v.v.:

gen byte newvariable = ! (first2>last1 | first1>last2)
or equivalently:
gen byte newvariable = first2<last1 & first1<last2

Perhaps you need <=, >= rather than <, >.

-----Original Message-----
[] On Behalf Of Nanlesta
Sent: Thursday, 30 December 2010 3:14 PM
Subject: st:Creating a variable from overlapping intervals

Dear Statalist,

My apologies for this very simple coding question.  While I know what
to do conceptually, I appear to get lost in the coding.
I am trying to determine if the participants in my study have
concurrent sexual relationships.  For each partner of the participant,
I have the number of days(or months or years) ago they first and last
had sex with that partner.  I am attempting to write a code to create
one variable that would use all that information to tell me if the
partnership is concurrent.

Essentially:  If the first sex month (or first sex & last sex) of
partner 2 occurs within the first and last sex months of partner 1,
then newvariable=1

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