Multiclass Confusion Matrix Reduction Method and Its Application on Net Promoter Score Classification Problem

The current paper presents a novel method for reducing a multiclass confusion matrix into a 2×2
version enabling the exploitation of the relevant performance metrics and methods such as the receiver operating characteristic and area under the curve for the assessment of different classification algorithms. The reduction method is based on class grouping and leads to a special type of matrix called the reduced confusion matrix. The developed method is then exploited for the assessment of state of the art machine learning algorithms applied on the net promoter score classification problem in the field of customer experience analytics indicating the value of the proposed method in real world classification problems.