Error in first. and last. statement

[Shivi82]

data ttt (drop=value period);

set testing;

by region;

if first.region and last.region then output ttt;

else output =duplicate;

run;

I get the error message that variable duplicate is uninitialized. PLease advice.

[Kurt_Bremser]

That's very simply because "duplicate" is not in the input data set.

[KachiM]

It is not due to FIRST. or LAST.

Place the data set names in the Output like:

data ttt (drop=value period) duplicate;

[Kurt_Bremser · Accepted solution]

And drop the erroneous equal sign

[Shivi82]

Just one more thing - as you mentioned duplicate in  the data step statement, would it create a new dataset which will capture other values excluding the first and the last obs of the group.