Table 5. Confusion matrix between the observed and predicted values of two hardness classes based on the average of 100 times of 10-fold cross validation using the most accurate predictive model (i.e., model 40) for hard90.

		Observed
		Hard	Soft	Total	User's accuracy
Predicted	Hard	18.99	2.02	21.01	90.39
	Soft	10.01	108.98	118.99	91.59
	Total	29	111	140
	Producer's Accuracy	65.48	98.18		91.41