Data from public health databases are typically formatted such that each record represents one person (or case report). Once these data have been geocoded, they need to be aggregated before linking to denominator and ABSM data. Before aggregating, however, one should exclude all records that are not geocoded, do not meet the case definition, or are missing data on the important covariates (e.g. age, in the case of simple age-standardized analyses; age, sex, and race/ethnicity in the case of more complex stratified analyses).

One can think of the basic unit of aggregation as a cell, defined by age and other covariates, within an area/geocode. Once aggregated, this cell within an area can be linked to a relevant population denominator. The cell contains a count of all cases within that area that meet the specified age and other covariate criteria. Since our goal is eventually to create rates, we call this count of cases the “numerator.”

DATA Step1a ;
SET rawcase ;

IF 0<=AGE<15 THEN AGECAT=1 ;
IF 15<=AGE<25 THEN AGECAT=2 ;
IF 25<=AGE<45 THEN AGECAT=3 ;
IF 45<=AGE<65 THEN AGECAT=4 ;
IF AGE>=65 THEN AGECAT=5 ;
RUN ;

PROC FREQ DATA=Step1a NOPRINT ;
TABLES AREAKEY*AGECAT /OUT=Step1b ;
RUN ;