January 6th, 2014, 6:05 pm
Assuming the change in stock price P from one period (t1) to the next (t2) is small, we can calculate returns using either:(Pt2 - Pt1)/Pt1-or-ln (Pt2/Pt1)For small changes, either method outputs the same values. This I have verified empirically. I understand that if x is log normally distibuted, then log(x) is normally distributed. And we would like to work with normal distributions in our analyses. Given all of the above, what exactly is the meaning fof "Log Returns"? We're not taking the logarithm of returns above, are we? We're calculating the returns by taking either the logarithm of Pt2/Pt1 -or- logarithm of (Pt2 - Pt1)/Pt1, both of which happen to give the same values at very small changes in the price. However, we're not taking the logarithm of the return itself, are we? Is the term "log returns" misleading -or- am I missing something? Isn't the distribution of (Pt2 - Pt1)/Pt1 distributed normally anyway (with fat tails may be), even without needing to apply any logarithm?Thanks in advance.