text: Fisher takes the geometric mean of the two. Dorbish Bowley takes the simple mean, Fisher takes the geometric mean. किसका? इन्ही दो का, Laspeyres and Paasche. When you want to take the geometric mean of a, b, you go under root of ab. When you want to take the geometric mean of Laspeyres, Paasche, you multiply, take the root.