topic Re: SAS way for calculating YoY change in SAS Programming

SAS way for calculating YoY change

caveman529 — Wed, 20 Aug 2014 00:35:47 GMT

Dear All:

Could someone tell me how to calculate year to year sales changes when the data is at quarterly interval?

The data looks like:

patient YEAR QTR visit

I do the following

proc sort data=t1 out=t2;

by patient qtr year;

run;

data t3;

set t2;

by patient qtr year;

if first.patient or first.qtr then

lagvisit = .;

else lagvisit = lag(visit);

run;

But the resulting table is not correct. Could someone here tell me why?

Re: SAS way for calculating YoY change

Reeza — Wed, 20 Aug 2014 01:28:56 GMT

Lag shouldn't be used in a conditional statement (if/then).

Conditional Use of LAG - sasCommunity

Re: SAS way for calculating YoY change

caveman529 — Wed, 20 Aug 2014 01:50:11 GMT

Hi, Reeza:

Thanks for the tips. I'll refrain from using the lag function in if/then situation. Could you tell me the most efficient way to achieve the task? I think some kind of proc sql should do the trick, but the syntax would be ugly.

Re: SAS way for calculating YoY change

PGStats — Wed, 20 Aug 2014 02:02:15 GMT

All you need is to keep the lag out of the conditional block:

proc sort data=t1 out=t2;

by patient qtr year;

run;

data t3;

set t2;

by patient qtr year;

lagvisit = lag(visit);

if first.qtr then lagvisit = .;

run;

Re: SAS way for calculating YoY change

caveman529 — Wed, 20 Aug 2014 15:59:07 GMT

This works great