1. The problem statement, all variables and given/known data Hello! I am trying to compute the bi-geometrical mean on data that contains negatives. But before that I wanted the test the formula that accounts only for positive values using the sum of their logarithms. By doing so I don't get the result I compute by using the "usual" geo mean formula: for values between 0 and 1: ((1+a1) * (1+a2) * ....(1+ aN)) ^(1/n) - 1 for other positive values: (last value / initial value) ^ (1/number of periods) - 1 2. Relevant equations Here is the example: 1,062 1,252 1,587 1,934 2,519 Geometric mean = (2519 / 1062) ^ (1/5) - 1 = 18.86% 3. The attempt at a solution Using the formula log g = sum of logs of each value (see picture attached) log g = (LOG(1062)+LOG(1252)+LOG(1587)+LOG(1934)+LOG(2519))/number of periods I get geo mean = 0.505, which is nowhere close to 18.86% What am I doing wrong? Thank you!