Create Threshold

Synopsis

This operator creates a user defined threshold for crisp classification based on the prediction confidences (soft predictions). This threshold can be applied by using the Apply Threshold operator.

Description

The threshold parameter specifies the required threshold. The first class and second class parameters are used for specifying the classes of the ExampleSet that should be considered as first and second class respectively. The threshold created by this operator can be applied on the labeled ExampleSet using the Apply Threshold operator. Should it occur that the confidence for the second class is greater than the given threshold then the prediction is set to this second class otherwise it is set to the first class. This can be easily understood by studying the attached Example Process.

The Apply Threshold operator applies the given threshold to a labeled ExampleSet and maps a soft prediction to crisp values. The threshold is provided through the threshold port. Mostly the Create Threshold operator is used for creating thresholds before they are applied using the Apply Threshold operator.

Among various classification methods, there are two main groups of methods: soft and hard classification. In particular, a soft classification rule generally estimates the class conditional probabilities explicitly and then makes the class prediction based on the largest estimated probability. In contrast, hard classification bypasses the requirement of class probability estimation and directly estimates the classification boundary.

Output

output

This port delivers the threshold. This threshold can be applied on a labeled ExampleSet by using the Apply Threshold operator.

Parameters

Threshold

This parameter specifies the threshold of the prediction confidence. It should be in range 0.0 to 1.0. If the prediction confidence for the second class is greater than this threshold the prediction is set to second class (i.e. the class specified through the second class parameter) otherwise it is set to the first class(i.e. the class specified through the first class parameter).

First class

This parameter specifies the class which should be considered as the first class.

Second class

This parameter specifies the class which should be considered as the second class.