How to merge multiple observations into one row

[LarissaW]

This is my current dataset

I want a dataset like below

[Tom · Accepted solution]

What is the RULE that allows that transformation?

Is it:

Spoiler

Take the maximum value?

proc summary data=have;
  by pid;
  var _numeric_;
  output out=want max= ;
run;

Or perhaps:

Spoiler

Take the total value?

proc summary data=have;
  by pid;
  var _numeric_;
  output out=want sum= ;
run;