Question

I have a range of weekly variables describing a person’s “status” (from week 1, 2010 to 2012 week 17).

The variables are given by:

y_1001, y_1002,...y1052, y1101, y1102,......y_1217

I define the period of variables like this:

%let period = y_1001-1052 y_1101-y1148;

I also have a treatment period given as a start date and an end date. My challenge is to find the status given by the y_ variables in the week after the person stops the treatment.

I am not too familiar with SAS, but my idea was to “pick” the correct y_ variable based on a week counter, say by counting the number of weeks since the beginning of the period (week 1 in 2010) and until the date where the treatment ends.

I get the weeks until end of treatment like this

week_count = 1 + intck( 'week.2', '1JAN2010'd, end_treatment_date, 'd');

But how can I retrieve the corresponding y_ variable based on this count?

After fruitless search on how to loop over the period variables and pick the number corresponding to the week_count variable for each person, I thought about going a different way… say something like this.

array weeks(*) .
do i = 1 to dim(weeks) by 1;
  if week_count = i then end_status = y_10&i;
end

…but with modifications to take into account that there is a mismatch between the dimension of the array and the number of weeks and years.

But then my challenge is to make the following part work…

if week_count = i then end_status = y_10&i;

How can I make SAS pick the right y_ variable based on the loop index? This seems like a really simple problem, but somehow I have not managed to find a solution. Is there no way to use the variable “i” as input in defining the correct y_ variable?

Would really appreciate if somebody could throw some hints.

Answer 1

I think you want:

if week_count = i then end_status = weeks{i};