Array?

[matoma]

I have a data set with 3 families and each family has an income value for months 1-12. I'm trying to determine how many months each family had an income that was less than two thirds of the income of the previous month. To do that I want to find out which months had income that was less than two thirds the income of the previous months, then add them up. I figure an array would be easiest but I'm not totally sure how to set that up. I'll attach what the data set looks like. Any advice would be appreciated. 

[PaigeMiller · Accepted solution]

2/3 of the income of the previous month is not defined for the first month. So

data want;
    set have;
    array faminc faminc1-faminc9;
    sum=0;
    do i=2 to 9;
         if faminc(i)<faminc(i-1)*2/3 then sum=sum+faminc(i);
    end;
    drop i;
run;