Be careful with missing values

[Kevin_Graduate]

The numeric value for a is 18735.

data work.test;
a='18APR11'D;
b=.;
output;
run;

data work.test2;
set work.test;
if a-b>1825 then c=1;
if a-b<1825 then c=2;
run;

proc print data=work.test2;
run;

Result: c=2.

Why c=2? It makes more sense if it is 1.

[SteveDenham]

The value for a-b is ., which is less than any value. I would expect c=2 as the only possible result.

Steve Denham

[MichelleHomes]

Hi Kevin,

If you want missing values to be ignored use SAS functions instead...

e.g.
if sum(a,-b)>1825 then c=1;
if sum(a,-b)<1825 then c=2;

this will then ignore the missing value and you will get your desired c=1 as your result.

This is described in the SAS documentation and in the SAS programming 1 course.

Kind Regards,
Michelle