Skip to main content
Cross Validated

Return to Answer

added 22 characters in body
Source Link
cardinal
cardinal
  • 27.3k
  • 8
  • 105
  • 140

Without any additional assumptions on $X$ and $Y$, it is not possible to deduce the covariance of the log knowing the initial covariance. In the other hand, if you were able to compute $Cov(X,Y)$$\mathrm{Cov}(X,Y)$ from $X$ and $Y$, what prevents you from calculating $Cov(log(X), log(Y))$$\mathrm{Cov}(\log(X), \log(Y))$ from $log(X)$$\log(X)$ and $log(Y)$$\log(Y)$ directly?

Without any additional assumptions on $X$ and $Y$, it is not possible to deduce the covariance of the log knowing the initial covariance. In the other hand, if you were able to compute $Cov(X,Y)$ from $X$ and $Y$, what prevents you from calculating $Cov(log(X), log(Y))$ from $log(X)$ and $log(Y)$ directly?

Without any additional assumptions on $X$ and $Y$, it is not possible to deduce the covariance of the log knowing the initial covariance. In the other hand, if you were able to compute $\mathrm{Cov}(X,Y)$ from $X$ and $Y$, what prevents you from calculating $\mathrm{Cov}(\log(X), \log(Y))$ from $\log(X)$ and $\log(Y)$ directly?

Source Link
ThePawn
ThePawn
  • 1.2k
  • 6
  • 7

Without any additional assumptions on $X$ and $Y$, it is not possible to deduce the covariance of the log knowing the initial covariance. In the other hand, if you were able to compute $Cov(X,Y)$ from $X$ and $Y$, what prevents you from calculating $Cov(log(X), log(Y))$ from $log(X)$ and $log(Y)$ directly?