Why does SAS give the output of a calculation in the the row below the initial values? How to solve?

[KarolineN]

Dear SAS Community,

I am having an issue with SAS that I have not experienced before when multiplying two variables. When I conduct the following calculation: 

data dataset_2;
Ser_Occ=_FREQ_*Ntot;
set dataset_1;
run;

I get this result: 

I do not understand why the values of the resulting new varibale "Ser_Occ" are shifted one row down. That is, the result of the calculation of row 1, is displayed in row 2, and so on. I would like to get the result of the calculation in the same row.

I would be very grateful for some feedback from you on why SAS studio does this and how to get the values in the same row? Could it for example have to do with the settings or the underlying format of _FREQ_ which was computed using proc summary statement? 

Best regards,

Karoline

[PaigeMiller]

Your screen capture is too small to read. Can you please provide the data as just plain old text and paste it into your message so we can read it?

[Kurt_Bremser]

data dataset_2;
Ser_Occ=_FREQ_*Ntot;
set dataset_1;
run;

The read of a dataset occurs where you wrote the SET statement; since you do your calculation before the read, it uses the values from the previous observation (or missing values in the first observation).

Keep in mind that, by definition, all variables from input datasets are automatically retained, so not set to missing at the beginning of a data step iteration.

[KarolineN]

Thank you very much @Kurt_Bremser. I see the problem and now understand how the placement of the code (before/after) the set statement makes a difference!

Best regards, Karoline

[Kurt_Bremser]

The nice thing about a (basically) interpreter language is that you can quickly test such minor code changes and inspect the results for the effects. See Maxim 4.

And such tinkering lets you gain an insight into the mechanics of the data step, which may be overwhelming at first, but offer a VERY wide field of options to the developing SAS hacker.