Hi, I need to explore some interactions in my dataset, but I don't understand the code I was provided with (below). In my case, I have 5 age categories (under 12, 12-29, 30-64, 65-79, and 80 and older), and the exposure (COPD) and outcome (neurological disease) are both binary (0,1). How would I code this? Do I need to make a dummy variable for each age category? I'd really appreciate any help. proc logistic data=arcus; class arcus (ref="0") / param=ref; model chd69 (event="1")=age50|arcus; contrast 'arcus vs. no for age<50' arcus 1 age50*arcus 0 / estimate=both; contrast 'arcus vs. no for age>=50' arcus 1 age50*arcus 1 / estimate=both; contrast 'age50 vs. no with arcus' age50 1 age50*arcus 0 / estimate=both; contrast 'age50 vs. no without arcus' age50 1 age50*arcus 1 / estimate=both; contrast 'arcus and age50 vs. neither' age50 1 arcus 1 age50*arcus 1 / estimate=both; run;
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