data cobb; input k l y; datalines; 40 40 32 40 120 45 40 200 43 40 320 60 80 40 36 80 80 33 80 160 62 80 280 86 120 120 55 120 200 66 120 320 94 160 40 38 160 80 62 160 160 88 160 240 78 200 120 81 200 200 81 200 320 115 240 40 39 240 160 90 240 240 90 240 280 100 280 80 68 280 120 60 280 240 115 280 320 112 320 40 54 320 120 118 320 200 134 320 320 125 ; data cobb; set cobb; lk = log(k); ll = log(l); ly = log(y); proc reg data = cobb; model ly = lk ll / covb; test lk + ll = 1; run;