Creating indicators for a time-varying response variable

[silversta]

Hello all,

I have data that is structured as below for example. I want to create the injury indicator based on the interval_start and interval_end dates. The indicator should be 0 until the first injury is experienced within the interval dates, at which point it should be 1. The indicator will remain 1 for those without a second injury and needs to change to 2 once the second injury occurs within the interval dates and remain 2 for the rest of the records with that id. 

id    injury_date1   Injury_date2      interval_start      interval_end       injury_indicator

1     7/14/2008           .                    5/1/2008             5/31/2008                0

1     7/14/2008           .                    6/1/2008             6/30/2008                0

1     7/14/2008           .                    7/1/2008             7/31/2008                1

1     7/14/2008           .                    8/1/2008             8/31/2008                1

1     7/14/2008           .                    9/1/2008             9/30/2008                1

1     7/14/2008           .                    10/1/2008           10/31/2008              1

2     6/6/2009        10/20/2009        4/1/2009             4/30/2008                0

2     6/6/2009        10/20/2009        5/1/2008             5/31/2008                0

2     6/6/2009        10/20/2009        6/1/2008             6/30/2008                1

2     6/6/2009        10/20/2009        7/1/2008             7/31/2008                1

2     6/6/2009        10/20/2009        8/1/2008             8/31/2008                1

2     6/6/2009        10/20/2009        9/1/2008             8/30/2008                1

2     6/6/2009        10/20/2009        10/1/2008           10/31/2008              2

2     6/6/2009        10/20/2009        11/1/2008           11/30/2008               2

2     6/6/2009        10/20/2009        12/1/2008           12/31/2008              2

2     6/6/2009        10/20/2009        1/1/2008             1/31/2008                2

I have tried to accomplish this through a series of data steps with no success. Any help provided would be most appreciated!

[ChrisNZ · Accepted solution]

This should work:

data WANT;
  set HAVE ;
  by ID;
  if first. ID then INJURY_INDICATOR=0;
  if INTERVAL_START <= INJURY_DATE1 <= INTERVAL_END 
   | INTERVAL_START <= INJURY_DATE2 <= INTERVAL_END then INJURY_INDICATOR+1;
run;

Please check the examples you provide. You seem to have mixed 2008 and 2009. Spend more time checking to save our time.

[silversta]

My apologies, I meant to change those to 2009. Thank you for your help!