What Is Discriminant Analysis?

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A technique for classifying data, discriminant analysis works with responses to questions posed in the form of variables and other factors that serve as predictors. It is also used to find the contribution of every parameter in dividing the groups. Identifying one or more linear combinations of the variables that have been chosen is how discriminant analysis does its work.

Key Takeaways

  • A model for determining membership in a group may be constructed using discriminant analysis.The model is made up of a discriminant function or, for more than two groups, a set of discriminant functions that is premised on linear relationships of the predictor variables that provide the best discrimination between the groups.There are two types of discriminant analysis: linear and quadratic.If there are more than two groups, the model will consist of discriminant functions.

Discriminant Analysis Explained

Discriminant analysis (DA) is a multivariate technique which is utilized to divide two or more groups of observations (individuals) premised on variables measured on each experimental unit (sample) and to discover the impact of each parameter in dividing the groups.

In addition, the prediction or allocation of newly defined observations to previously specified groups may be examined using a linear or quadratic function for assigning each individual to existing groups. This can be done by determining which group each individual belongs to.

A system for determining membership in a group may be constructed using discriminant analysis. The method comprises a discriminant function (or, for more than two groups, a set of discriminant functions) that is premised on linear combinations of the predictor variables that offer the best discrimination between the groups. If there are more than two groups, the model will consist of discriminant functions. After the functions have been constructed using a sample of instances for which the group membership is known, they may be applied to fresh cases that contain measurements for the predictor variables but whose group membership is unknown.

Assumptions

  • Samples ought to be free from one another and independent.The variables used as predictors should have a multivariate normal distribution, and the variance-covariance matrices for each group should be the same.It is presumable that cases cannot correspond to more than one group since group membership is considered mutually exclusive (that is, no case belongs to more than one group) (that is, all cases are members of a group).If group membership is based on values of a continuous variable, then consider using linear regression to take advantage of the richer information offered by the constant variable. The procedure is most effective when group membership is a truly categorical variable.

Types

Linear and quadratic discriminant analysis are the two varieties of a statistical technique known as discriminant analysis.

#1 – Linear Discriminant Analysis

Often known as LDA, is a supervised approach that attempts to predict the class of the Dependent Variable by utilizing the linear combination of the Independent Variables. It is predicated on the hypothesis that the independent variables have a normal distribution (continuous and numerical) and that each class has the same variance and covariance. Both classification and conditionality reduction may be accomplished with the assistance of this method.

#2 – Quadratic Discriminant Analysis

It is a subtype of Linear Discriminant Analysis (LDA) that uses quadratic combinations of independent variables to predict the class of the dependent variable. The assumption of the normal distribution is maintained. Even if it does not presume that the classes have an equal covariance. The QDA produces a quadratic decision boundary.

Application

Not only is it possible to solve classification issues using discriminant analysis. It also makes it possible to establish the informativeness of particular classification characteristics and assists in selecting a sensible set of geophysical parameters or research methodologies.

Businesses use discriminant analysis as a tool to assist in gleaning meaning from data sets. This enables enterprises to drive innovative and competitive remedies supporting the consumer experience, customization, advertising, making predictions, and many other common strategic purposes.

The human resources function is to evaluate potential candidates’ job performance by using background information to predict how well candidates would perform once employed.

Based on many performance metrics, an industrial facility can forecast when individual machine parts may fail or require maintenance.

The ability to anticipate market trends that will have an impact on new products or services is required for sales and marketing.

Example

Let us consider an example of where the discriminant analysis can be used.

Consider that you are in charge of the loan department at ABC bank. The bank manager asks you to find a better way to give loans so bad debt and defaults are reduced. You have a financial management background, so you decide to go with discriminant analysis to understand the problem and find a solution. 

The creation of a credit risk profile for existing customers by a bank’s loan department to determine whether new loan applicants pose a credit risk is a canonical example of dynamic financial analysis. Other examples include determining whether or not new consumers will make a purchase, whether or not they will be loyal to a certain brand, whether or not a sales approach will have a poor, moderate, or strong success rate, or which category new buyers will fall into.

In addition to this, it shows which of the predictors are the most differentiating (have the highest discriminate weights), or, to put it another way, which dimensions differentiate these consumer segments the most effectively from one another, as well as the reasons why respondents fall into one group as opposed to another group. In a nutshell, it is a method for categorizing, differentiating, and profiling individuals or groups.

Discriminant Analysis vs. Logistics Regression

  • When the dependent variable is dichotomous, logistics regression (LR) is the method of choice. However, when it is nominal, discriminant analysis (DA) is the method of choice (more than two groups).LR will take both continuous and categorical predictor variables. DA will only accept continuous (or dummy) predictors and will not accept any category predictors at all.When the more stringent DA assumptions are not satisfied. LR is favored over DA as the analysis method (LR requires fewer assumptions).DA necessitates multivariate normality, whereas LR may tolerate significant departures from the expected value of the variable(s).Compared to DA, LR may be used for a wider variety of research problems.In LR, dummy variables are generated on your behalf automatically, while in DA, the researcher is responsible for producing them.

Discriminant Analysis vs. Cluster Analysis

  • In contrast to discriminant analysis, which is an illustration of supervised learning, cluster analysis illustrates unsupervised learning.The object category is unknown while doing cluster analysis. The object category is already established before beginning discriminant analysis.In the process of cluster analysis, a rule of categorization is presented. The discriminant analysis does not provide a rule of categorization.The goal of training in cluster analysis is to get familiar with each item’s category. The goal of training in discriminant analysis is to become familiar with the classification rule.

This article has been a guide to Discriminant Analysis and its Explanation. Here, we explain the concept with its Assumptions, Types, Application and Example. You may also find some useful statistics articles here:

Fisher’s linear discriminant is used in statistics and other fields to find a linear combination of features that characterizes or differentiates atleast two classes of objects or events. Linear discriminant analysis is believed to be a generalization version of Fisher’s linear discriminant. It seeks to find such a linear combination.

A good example of a generative model is the quadratic discriminant analysis (QDA). The QDA assumes that the distribution of each class is Gaussian. The class-specific prior is only the percentage of total data points that may be assigned to that particular class. The average of the input variables that are associated with a particular class constitutes the class-specific mean vector.

The linear method An estimate of the likelihood that a fresh set of inputs belongs to each class may be obtained by discriminant analysis. LDA generates predictions by estimating the chance that a fresh set of inputs belongs to each class. These probabilities are then used to make decisions. The class that achieves the highest probability is designated as the output class, and a conclusion may be drawn from the data. Any of the discriminant analysis classifications can be used to obtain the results.

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