Hello everyone,  Here is an example for which I have some difficulties: data test; length VAR1 $ 1; input VAR1 $ VAR2 VAR3; datalines; A 1 157 A 2 130 A 3 67 A 4 -54 A 5 -89 A 6 -101 B 1 500 B 2 456 B 3 234 B 4 -10 B 5 -303 B 6 -409 C 1 239 C 2 210 C 3 150 C 4 -2 C 5 -30 C 6 -44   The number of records for A, B, C etc is fixed and equal to 6. VAR3 is sorted from high to low and contains negative values.   The steps to perform are the following:   1) For each VAR1 (A, B, C etc) identify VAR2 and VAR3 for which VAR3 is negative for the first time 2) Identify VAR2 and VAR3 of the record just above 3) Make an operation with values obtained from 1) and 2). See example below:   Example: for VAR1 = A 1) VAR2 = 4 VAR3=-54 2) VAR2 = 3 VAR3=67 3) Make an operation with 1) and 2):      4+ (4-3)*[67/(67-(-54))]   Thank you! ... View more