topic Re: Model for Correlated data in Statistical Procedures

Model for Correlated data

analyst_work — Thu, 18 Feb 2021 14:42:24 GMT

Hi,

I am trying to decide which model would best be suited for my study. I have two continuous variables A (independent) and B (response). We are measuring these for 20 hospitals for each month across the year 2020 - so each hospital has 12 values for each month for each variable. I am currently using proc genmod with the repeated statement to account for clustering within each hospital. Wondering what might be a good way to account for time in this case? Sharing my code below:

proc genmod data = dataset;

class hospid;

model B = A ;

repeated subject = hospid;

run;

Re: Model for Correlated data

StatDave — Thu, 18 Feb 2021 15:57:57 GMT

You can specify your Month variable in the WITHIN= option in the REPEATED statement and then, if desired, use a correlation structure such as TYPE=AR that allow the correlation strength to diminish with time.

Re: Model for Correlated data

analyst_work — Fri, 19 Feb 2021 20:19:02 GMT

Is there a way to replicate this using proc glimmix instead?

Re: Model for Correlated data

jiltao — Fri, 19 Feb 2021 23:41:01 GMT

proc glimmix data = dataset;
class hospid month;
model B = A ;
random month / residual subject = hospid type=ar(1);
run;

Re: Model for Correlated data

analyst_work — Tue, 23 Feb 2021 13:14:49 GMT

Thanks! One follow-up question - my variable A is a continuous variable, and will not appear in the class statement. How do I use lsmeans (or something similar) to get the rate estimates in this case? Thanks!

Re: Model for Correlated data

jiltao — Tue, 23 Feb 2021 17:55:00 GMT

What exactly do you want to estimate for A?

Depends on what you want to estimate, you might use the S option in the MODEL statement to get the slope estimate for A, or use the ESTIMATE statement. For example,

proc glimmix data = dataset;
class hospid month;
model B = A ;
random month / residual subject = hospid type=ar(1);

estimate 'response when A=5' int 1 A 5;
run;