Aggregate analysis in SAS

If there are aggregate data rather than individual data, analysis in SAS is less intuitive compared to STATA.

/* the aim of this analysis is to assess if the proportion of infection is changing across different years */

data xtrct;
input yr inf mech upgr other;/*infection has number of infection patients */

cards;
2000 12 7 0 40
2001 10 7 1 52
2002 34 13 4 24
2003 30 27 6 21
;

/* We need to convert this wide data set into long dataset*/
data trite;
set xtrct;
ninf=mech+upgr+other; /*total number of non infection patients */
ARRAY a(1:2) inf ninf;
DO t = 1 to 2 ;
num= a(t) ;
indicinf=t; /*indicator if num represents infections or non infections */
OUTPUT ;
END ;

proc print;
run;

/* The data table should be as follows. Note num corresponds to number of cases with infection and without infection.*/

Obs	yr	inf	mech	upgr	other	ninf	inf	infi	num
1	2000	12	7	0	40	47	12	1	12
2	2000	12	7	0	40	47	12	2	47
3	2001	10	7	1	52	60	10	1	10
4	2001	10	7	1	52	60	10	2	60
5	2002	34	13	4	24	41	34	1	34
6	2002	34	13	4	24	41	34	2	41
7	2003	30	27	6	21	54	30	1	30
8	2003	30	27	6	21	54	30	2	54

/* To assess the proportion of patients with infections is same over the 3 year period */

proc freq order=data;
title3 '(Two one-way tables followed by a 2x2 table)';
table yr*indicinf / chisq;
weight num;
run;

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The output is here.