Computing, Artificial Intelligence and Information Technology
Differentiating between good credits and bad credits using neuro-fuzzy systems

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Abstract

To evaluate consumer loan applications, loan officers use many techniques such as judgmental systems, statistical models, or simply intuitive experience. In recent years, fuzzy systems and neural networks have attracted the growing interest of researchers and practitioners. This study compares the performance of artificial neuro-fuzzy inference systems (ANFIS) and multiple discriminant analysis models to screen potential defaulters on consumer loans. Using a modeling sample and a test sample, we find that the neuro-fuzzy system performs better than the multiple discriminant analysis approach to identify bad credit applications. Further, neuro-fuzzy systems have many advantages over traditional computational methods. Neuro-fuzzy system models are flexible, more tolerant of imprecise data, and can model non-linear functions of arbitrary complexity.

Introduction

Between 1985 and 1996, the number of personal bankruptcy cases filed in the US rose from 341,000 to 1.1 million, and the rate of bankruptcy per 100,000 adults increased from 203 to 596 (Nelson, 1999). At the same time, competition in the consumer credit market has become intense. Consequently, financial institutions are faced with the dilemma of trying to increase loan volume without unduly increasing their exposure to default. Therefore, to screen loan applications, new techniques such as neuro-fuzzy models (compared to the traditional statistical models) should be explored to help predict potential default loans more reliably.

The loan officers of financial institutions use many techniques such as statistical models, credit scoring models, or rules that have been developed through experience to evaluate consumer loan applications. The use of a technique depends on the complexity of the institution, and the size and the type of the loan. Analytical models, such as empirically derived credit scoring systems (based on historical data), use the probability of default to predict the relative creditworthiness of a loan applicant. But, the credit-scoring model does not completely eliminate the human element. The selection of cutoff scores is a subjective decision. Moreover, the evaluation of applicants that have scores between the accept-scores and the reject-scores is quite subjective. Thus, to be more objective in evaluating loan applications, many institutions are exploring the use of artificial intelligence techniques such as artificial neural systems and fuzzy logic.

Fuzzy logic, a relatively new, rule-based development in artificial intelligence, tolerates imprecision and even uses it to solve problems that were not solved before. Fuzzy sets and fuzzy logic systems are based on the way the brain deals with inexact information. On the other hand, neural networks are modeled after the physical architecture of the brain. Neural networks are specialized hardware or software that emulate the processing patterns of the human brain. Fuzzy logic and neural networks are complementary technologies in the design of intelligent systems. Each method has merits and demerits. Artificial neural systems suffer from their inability to explain the steps used to make decisions and incorporate rules in their architecture. Neural fuzzy systems address some of the shortcomings of artificial neural network tools. Fuzzy logic systems often deal with issues such as reasoning on a higher level than neural networks. However, since fuzzy systems do not have much learning capability, it is difficult for a human operator to tune the fuzzy rules and membership functions from the training data set. Thus, to reap the benefits of both fuzzy systems and neural networks, a promising approach is to merge fuzzy logic and neural networks into an integrated system. Neuro-fuzzy systems represent one of the ways in which fuzzy systems and neural networks can be merged.2

This study investigates the classification accuracy of neuro-fuzzy systems to screen consumer loan applications. To construct a model, the study uses a pooled data set of consumer loan applications from nine different credit unions, and applies neuro-fuzzy system. The objective of this study is to evaluate the effectiveness of neuro-fuzzy model to identify problem loans. Secondly, we compare the performance of neuro-fuzzy model with the statistical linear discriminant analysis models. Our analysis indicates that the neuro-fuzzy models' performance in evaluating potential loan defaulters is statistically superior to the performance of linear discriminant analysis. In addition, neuro-fuzzy models do not require any restrictive assumptions of the statistical models, and are flexible enough to permit the loan officer to incorporate new rules for loan evaluation. This study is divided into six parts: Section 2 reviews the existing literature on the use of fuzzy logic and neural networks in finance, and illustrates the current applications; Section 3 describes the data used in this study; Section 4 explains the design of a neural fuzzy system model and a linear discriminant analysis model to screen consumer loan applications; Section 5 analyzes the results of loan classifications using discriminant analysis and neuro-fuzzy inference, and finally, Section 6 concludes and summarizes the study.

Section snippets

Previous studies

Many studies highlight the use of artificial neural systems and fuzzy logic in financial management. Jensen (1992) illustrates the use of a standard backpropagation neural network for loan classification. The network's classification accuracy was in the range 76–80% on the holdout sample. However, the sample size of Jensen's study is very small at 125 applicants. Tam and Kiang (1992) compare the artificial neural system approach with a linear classifier, the logistic regression model, kNN

Description of the data set

To better understand the process of credit evaluation, and explore alternative quantitative models that can aid a loan officer in the credit union environment, we analyzed data from nine credit unions. We combined the data of loans made by these credit unions to form a pooled data set with a total of 790 observations.

Discriminant analysis model

Discriminant analysis involves the linear combination of the two (or more) independent variables that differentiate best between the a priori defined groups. This is achieved by the statistical decision rule of maximizing the between-group variance relative to the within-group variance; this relationship is expressed as the ratio of between groups to within group variance. The linear combinations for a discriminant analysis are derived from an equation that takes the form of Eq. (1).Z=W1X1+W2X2

Multiple discriminant analysis versus artificial neuro-fuzzy inference system (ANFIS)

Table 2 summarizes the empirical results of the discriminant analysis and ANFIS.

For the seven training samples, the discriminant analysis model's predictive accuracy ranges from 69.8% to 73.2%. Groupwise, the model correctly classified in the range of 83.6–85.6% of the 250 applications in Group 1 (good credit) and 56–62% of the 250 applications in Group 2 (bad credit). Similarly, for the hold out sample, the discriminant analysis model's classification accuracy ranges between 62.05% and 66.2%

Contribution of this study

Although mathematically derived credit-scoring systems (analytic) are a definite improvement over subjective judgmental (intuitive) methods to evaluate consumer loans, we can improve the method of credit scoring considerably through the use of artificial intelligence techniques such as expert systems, neural networks, fuzzy logic, and neuro-fuzzy systems. While expert systems have been extensively used by many organizations, neural networks and fuzzy systems have captured the attention of the

Uncited references

The following works are also of interest to the reader:

Jang and Gulley, 1995, Jang and Gulley, 1998

Acknowledgements

The authors would like to thank the two anonymous reviewers for their valuable comments and suggestions. The errors in this paper are solely the authors' responsibility.

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