Hi all, I am a new user of SAS. I have a data and I want to write a loop throug observations, but I don't know how to do it in SAS. Here is the data ID KN1 KN2 KN3 KN4 KN 103 1 3 4 999 2 105 5 5 2 6 5 119 999 999 2 6 2 176 8 5 6 4 3 201 5 4 8 999 2 206 999 3 999 2 4 230 6 7 4 999 2 I want to write a loop that from the fisrt subject to the last subject, if this subject's kn1-4 equals to 999, then change the 999 to the value of this subject's kn. Thank you very much!
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