I have the following issue in SAS: Consider the table below: Patient_ID Day Lipid_Levels First_Obs 0001 0 10.2 10.2 0001 1 11.6 10.2 0001 2 14.5 10.2 0001 3 10.5 10.2 0002 0 9.9 9.9 0002 1 10.7 9.9 0002 2 11.4 9.9 0002 3 11.1 9.9 0003 0 14.3 14.3 0003 1 17.2 14.3 0003 2 14.1 14.3 0003 3 14.5 14.3 I have a dataset named "indata" with the variable Patient_ID, Day, and Lipid_Level, and I need to create a new variable First_Obs that is equal to the first observation for a given patient ( i.e. the Lipid Level when the Day-within-Patient_ID value is equal to zero). Again, I have the first three columns, and I need to create the fourth. Any suggestions?? Thank you for your help.
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