Message-ID: <CAAjnpdjhFDAWrD9Pssewhss046vdFYdgPg7Crk7kYwoLqKBu6w@mail.gmail.com>
Date: 2019-01-12T17:55:30Z
From: Witold E Wolski
Subject: randomForest out of bag prediction
Hello,
I am just not sure what the predict.RandomForest function is doing...
I confused.
I would expect the predictions for these 2 function calls to predict the same:
```{r}
diachp.rf <- randomForest(quality~.,data=data,ntree=50, importance=TRUE)
ypred_oob <- predict(diachp.rf)
dataX <- data %>% select(-quality) # remove response.
ypred <- predict( diachp.rf, dataX )
ypred_oob == ypred
```
These are both out of bag predictions but ypred and ypred_oob are
actually they are very different.
> table(ypred_oob , data$quality)
ypred_oob 0 1
0 1324 346
1 493 2837
> table(ypred , data$quality)
ypred 0 1
0 1817 0
1 0 3183
What I find even more disturbing is that 100% accuracy for ypred.
Would you agree that this is rather unexpected?
regards
Witek
--
Witold Eryk Wolski