SAS way for calculating YoY change

Solved
Regular Contributor
Posts: 161

SAS way for calculating YoY change

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?

Accepted Solutions
Solution
‎08-19-2014 10:02 PM
Posts: 5,482

Re: SAS way for calculating YoY change

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;

PG

PG

All Replies
Super User
Posts: 23,296

Re: SAS way for calculating YoY change

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

Conditional Use of LAG - sasCommunity

Regular Contributor
Posts: 161

Re: SAS way for calculating YoY change

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.

Solution
‎08-19-2014 10:02 PM
Posts: 5,482

Re: SAS way for calculating YoY change

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;

PG

PG
Regular Contributor
Posts: 161

Re: SAS way for calculating YoY change

This works great

🔒 This topic is solved and locked.