I need help with my SAS code. I have a dataset (test) that have variables yearcase and case. Yearcase is a variable that indicates a 2-motor vehicle crash .Case is a binary variable that indicates each of the 2 cars involved in the crash. I want to create a dataset (test2) that only includes case=1( car that caused the crash) and case=0 (car that did not cause the crash). I want each yearcase (crash pair) to have the car that caused the crash and one that did not cause the crash. I want to exclude yearcases (2-motor vehicle crashes) in which both cars did not cause the crash (case=0) or in which both cars caused the crash (case=1). My code here yields the following output below. As you can see, I still have yearcases (crashes) in which either both cases caused the crash (case=1) or both cases did not cause the crash (case=0). I attempted to use flag variables nocase and bothcase but its not working. data test2;
set test;
retain nocase bothcase;
by yearcase;
if first.yearcase then case=nocase;
if last.yearcase then case=bothcase;
if bothcase=nocase then output;
run;
proc freq data=test2;
tables yearcase*case/norow nocol nopercent;
run;
Output looks like this:
case
yearcase case= 0 case= 1 Total
201410001 0 2 2
201410007 0 2 2
201410015 2 0 2
201410024 1 1 2
201410031 1 1 2
201410036 0 2 2 How can I make sure I only have yearcases (2-motor vehicle crashes) in which there is only 1 car that caused the crash (case=1) and another that did not (case=0)? I may need to use flag variables..but i'm unsure how to. Any help is greatly appreciated. Thank you
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