I've run a Random Forest in R using randomForest package.
The fitted forest I've called:
All I want to know is: When I type
fit.rf the output shows '% var explained' Is the % Var explained the out-of-bag variance explained?
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Yes %explained variance is a measure of how well out-of-bag predictions explain the target variance of the training set. Unexplained variance would be to due true random behaviour or lack of fit.
%explained variance is retrieved by randomForest:::print.randomForest as last element in rf.fit$rsq and multiplied with 100.
Documentation on rsq: rsq (regression only) “pseudo R-squared”: 1 - mse / Var(y). Where mse is mean square error of OOB-predictions versus targets, and var(y) is variance of targets.
see this answer also.