How do I lag the exposure to outcome by a year?

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New Contributor
Posts: 4

How do I lag the exposure to outcome by a year?

Hello,

 

I am looking to lag the exposure to outcome by a year. What I mean by this is that for a given year in my data, I want the exposure in one year to be associated with the outcome in the next, instead of the same year. This is because I want to avoid reverse causation. 

 

So if the exposure for 1999 is 26, I would want it to match with the outcome for 2000.

 

Here is my code without the lag:

 

PROC GENMOD data=data1;
CLASS StateID year (ref=first) event (ref=first);
MODEL Outcome =Exposure confounder / DIST=poisson LINK=log TYPE3 WALD offset=lnpop; 
REPEATED SUBJECT=stateid;
run;

 

I have an offset of state population and a repeated subject on stateID. Outcome is my main outcome and exposure is my main exposure. Confounder is a confounder. I do not think that the confounder should be lagged, just the main exposure and outcome.

 

Thanks so much!

Esteemed Advisor
Posts: 5,523

Re: How do I lag the exposure to outcome by a year?

Posted in reply to Revere2323

You could run your analysis on table data2 given by:

 

proc sql;
create table data2 as
select 
    a.*,
    b.Exposure as lastYearExposure
from 
    data1 as a inner join 
    data1 as b on a.stateId = b.stateId and b.year = a.year-1;
quit;

(untested)

 

PG
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