How to create new variable of two existed variables using their average?

[Nouf2]

Hello, 

I am new to SAS and I'm facing a problem figuring out:

How to create a new variable, which is the average of two existed variables (e.g. new variable=SBP, existed variable1=SPB1,  existed variable2=SPB2)

Thank you. 

[ballardw]

It really helps to provide a bit more structured details on the question. I am not sure whether you mean for each observation in a data set or of summarized data across the entire data set or a subset within the data.

If you want the mean on each observation of a data set then in a data step use the mean function.

data example;
    x=4;
    y=8;
    average=mean(x, y);
run;

Mean, and the associated other data step statistics functions like Min, Max, Std (standard deviation) will return the requested statistic based on the non-missing values of a list of variables (can be way more than 2).

[Nouf2]

Thank you for your reply. 

I mean I have a dataset with 14 different variables, two of them are named (SBP1 and SBP2).

I want to create a new variable that it is not part of the 14 existed variables of the dataset ( I will name it SBP). This new variable has to be the mean of both SBP1 and SBP2 variables. 

I believe the code has to contain some order to create a new variable then it calculate the mean to create the values of this new proposed variable. 

PS: I am taking Biostatistics course and we must use SAS, I am from medical background that's why it's tough for me to understand how it works! 

Thank you. 

[Tom · Accepted solution]

So if your existing dataset is named HAVE then data step will generate a new dataset named WANT that has the new SBP variable.

data want;
  set have;
  sbp=mean(sbp1,sbp2);
run;

So if you also DBP1 and DBP2 then you just add another line to create DBP also.

data want;
  set have;
  sbp=mean(sbp1,sbp2);
  dbp=mean(dbp1,dbp2);
run;