Values of $\alpha$, $\beta$ and $\gamma$ in ets in forecast package

Question

I am using the forecast package in R. I wanted to know how the ets() function finds the value of $\alpha$, $\beta$ and $\gamma$?

Is it by minimizing the SSE or some other criteria?

Answer 1

The default is MLE. The argument opt.crit controls the optimization criterion. from the help file:

opt.crit

Optimization criterion. One of "mse" (Mean Square Error), "amse" (Average MSE over first nmse forecast horizons), "sigma" (Standard deviation of residuals), "mae" (Mean of absolute residuals), or "lik" (Log-likelihood, the default).