On Mar 8, 2012, at 5:10 AM, shameek ghosh wrote:

Sir,
    This query is related to randomForest regression using R.

I have a dataset called qsar.arff which I use as my training set and
then I run the following function -

rf=randomForest(x=train,y=trainy,xtest=train,ytest=trainy,ntree=500)

   where train is a matrix of predictors without the column to be
predicted(the target column), trainy is the target column.I feed the same
data for xtest and ytest too as shown.

   On verifying I found, rf$mse[500] and rf$test$mse[500] are
different(the r-squares are also different).The predicted values of the
training target column and testing target column are also different.

  Should this happen , since I am using the training dataset as the
testing dataset? I expected that the test and training predictions would be
the same.

My inference from its name _random_Forest, was that it was _not_ "deterministic forest".

--

David Winsemius, MD
West Hartford, CT

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