Figure 4.

The effect on prediction error of omitting each subject from the set used to train the classifier. The diagonal shows the RMSE when the classifier was tested with the left-out subject. These data are also displayed in the panel above (filled circles), along with the RMSE when that subject was included in the training set (crosses). Subject 7 is the only example of a large cost to performance of being left out of the training set. Mean RMSE for the columns and rows is displayed in the bottom and leftmost panel, respectively, indicating that there was no cost of including any subject within the training set.