I've inherited some code that is not working as intended. Can someone decipher what this code is doing. It reads in excel spreadsheet and is supposed to calculate a mean over all quarters for each month on book value (1-36). I'd like to understand how it's doing this (if it is) and the reason for lag terms and initializing most recent quarter with _n. The log prints first. and last. values but I don't follow. The result is not as expected. %macro cum_corate36(grade); data LC_co_&grade.36; set LC_CO."&grade.36$A1:AQ37"N; run; proc sort; by MOB; run; data LC_co1_&grade.36; set LC_co_&grade.36; by MOB; _7Q3_n=_7Q3*1; array num _7Q3n _7Q2 _7Q1 _6Q4 _6Q3 _6Q2 _6Q1 _5Q4 _5Q3 _5Q2 _5Q1 _4Q4 _4Q3 _4Q2 _4Q1 _3Q4 _3Q3 _3Q2 _3Q1 _2Q4 _2Q3 _2Q2 _2Q1 _1Q4 _1Q3 _1Q2 _1Q1 _0Q4 _0Q3 _0Q2 _0Q1 _9Q4 _9Q3 _9Q2 _9Q1 _8Q4 _8Q3 _8Q2 _8Q1; array numlag1 lag1_7Q3 lag1_7Q2 lag1_7Q1 lag1_6Q4 lag1_6Q3 lag1_6Q2 lag1_6Q1 lag1_5Q4 lag1_5Q3 lag1_5Q2 lag1_5Q1 lag1_4Q4 lag1_4Q3 lag1_4Q2 lag1_4Q1 lag1_3Q4 lag1_3Q3 lag1_3Q2 lag1_3Q1 lag1_2Q4 lag1_2Q3 lag1_2Q2 lag1_2Q1 lag1_1Q4 lag1_1Q3 lag1_1Q2 lag1_1Q1 lag1_0Q4 lag1_0Q3 lag1_0Q2 lag1_0Q1 lag1_9Q4 lag1_9Q3 lag1_9Q2 lag1_9Q1 lag1_8Q4 lag1_8Q3 lag1_8Q2 lag1_8Q1; array numC C_7Q3 C_7Q2 C_7Q1 C_6Q4 C_6Q3 C_6Q2 C_6Q1 C_5Q4 C_5Q3 C_5Q2 C_5Q1 C_4Q4 C_4Q3 C_4Q2 C_4Q1 C_3Q4 C_3Q3 C_3Q2 C_3Q1 C_2Q4 C_2Q3 C_2Q2 C_2Q1 C_1Q4 C_1Q3 C_1Q2 C_1Q1 C_0Q4 C_0Q3 C_0Q2 C_0Q1 C_9Q4 C_9Q3 C_9Q2 C_9Q1 C_8Q4 C_8Q3 C_8Q2 C_8Q1; do over num; numlag1=lag(num); numC=num-numlag1; if MOB eq 1 then numC=.; end; C=mean(of C_:); keep MOB C; run; %mend; %cum_corate36(A);   ... View more