Hello I a new to SAS. I am creating a model that looks at the mean HIV viral load over time by gender, race/ethnicity, age group, residency, HIV risk exposure, and first (baseline) cd4 count. I know how the use the CLASS variable and ( "REF= option") to look at the difference in viral load by variable with only 2 levels. I want to compare results with a variable with more than 2 levels. For example race/ethnicity has 3 levels: Black, White, and Other. So I want to compare Black to White, Black to Other, and White to Other. Because I reference white the proc mixed in SAS will compare White vs Blacks and White vs Other. But I am trying to get Black Vs White without creating an new model. My proc mixed SAS code is below: *sort data set with average viral load; proc sort data = avgvlqrt out= avgvlqrt_sorted nodupkey; by rfa_id time avgvl; run; *Proc mix to look at youth mean viral load by residence, cd4, sex, race, and gender ; PROC MIXED data= avgvlqrt_sorted covtest noclprint noitprint method=reml PLOTS(MAXPOINTS=NONE); class sex_hars (ref="F") res_at_hiv_dx (ref="Urban") race_combined (ref="White") agegroupdx (ref="Adolesce") risk_hars_n (ref="Heterosexual") cd4base_dx (ref="< 200"); model avgvl= time sex_hars res_at_hiv_dx race_combined risk_hars_n agegroupdx cd4base_dx / solution; random time / subject=rfa_id Type= un vcorr; RUN;
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