title: creating an average score variable
body: <p>I have a dataset that goes as follows:</p>
  
  <p>an ID then his/hers storenumber then the amount of units they bought there.</p>
  
  <p>What i now need from that dataset is a variable that states the following: x buys per ID (for a specific store) (this score would thus be the same for different id's with the same storenumber) example:</p>
  
  <p>ID 1 and 2 have respectively 3 and 5 buys at store 1. then the variable i want would be (3+5)/2=4 then both ID's would get the variable average buys per ID for ID 1 and 2 is 4. </p>
  
  <p>I just cannot get the above done through spss.</p>