Your post: @Sonia2 wrote: I got the same question in exam but I want to clear some concepts, In same question can I use if in1 and in2 then output both; if in1 and not in2 then output no_grad_year; If not in1 and in2 then output no_income ; And my second question is when we give answer to question in exam if we look at else if in1 and not in2 then output no_grad_year; in output we will get some missing values if I want answer to question and answer is missing value then I’ll write for or type missing value or what ?? Please explain me. Please notice that IN1 and IN2 - each contains 1 for EXIST and 0 for absent.    As long as you didn't arrive to RETURN statement or to the end of the program, the data is still in the memory and you can write it to output, either the same dataset (making duplicates) or to other dataset.   Missing value in a variable is the result of nonexistance record on the dataset that contains this variable.       ... View more