What Is Multicollinearity? A Detail Guide

Oct 06, 2023 By Triston Martin

Many ask, What Is Multicollinearity? In a multivariate regression equation, multicollinearity occurs when there is a significant degree of correlation between multiple independent variables. It's possible to get skewed findings when trying to figure out how well each independent variable predicts the reliant variable in a mathematical approach because of multicollinearity. This may lead to less accurate estimates of the influence of independent variables due to the widening of the confidence levels caused by multicollinearity.

Understanding the Multicollinearity

Statisticians use multivariate regression models to forecast the value of a reliant variable relying on multiple independent variables. The result, goal, or criteria variable are all terms used to describe the dependent variable in research studies like these. Multivariate regression models, for instance, use a variety of factors to try to predict future stock returns, including P/E ratios, market capitalization, prior performance, and so on. There is a relationship between the stock return and a variety of financial data points.

This shows that independent variables that are in close proximity to one other are linked in some way, but the connection might be casual. If a company's prior success is linked to market capitalization, for example, then a company's market value will rise. To put it another way, multicollinearity may occur when two variables are strongly linked. Also, if an autonomous variable is calculated from several other variables within the information set or if two separate variables offer similar and repeating findings, this may occur as well.


A multicollinearity test makes it simple to find evidence of this phenomenon. Many factors contribute to collinearity, such as:

Selections Made

The first step is to make sure you ask the right questions to see whether a model has any instances of collinearity. As a second consideration, choosing dependent variables that are appropriate for the current situation is important. Collinearity is strongly influenced by the dataset that is used. Because of this, researchers need to conduct experiments that are well-designed and difficult to manipulate.

Variable Usage

The incorrect use of variables might also be a contributing factor. To prevent collinearity, researchers must be cautious in selecting or deleting variables. Researchers must also avoid using the same variables over and over again in their models. Users are committing a coding error when they utilize variables with the same name but distinct names or when they merge two variables into one. It could be difficult to estimate if total investment income contains two variables: the income created by stocks and bonds and the interest earned on savings accounts.

Correlation Degree

The primary reason is a high level of correlation between several variables. A regression model indicates that one variable has a considerable impact on another. As a consequence, the model as a whole may fall short of providing accurate findings. Multicollinearity is measured relative to a tolerance norm, which is a proportion of the variability inflation factor (VIF). The phenomena may arise if the multicollinearity variation inflation index is 4, which indicates a tolerance of 0.25 or less. However, if the values are 10 and 0.1 or below, multicollinearity is very certainly present.

Special Considerations

An easy technique to eliminate multicollinearity is to initially find and then eliminate all but one of several collinear independent variables. Multicollinearity may also be eliminated by integrating many collinear factors into one variable. It is thus possible to undertake a statistical analysis of just one independent variable as well as the given dependent variable.

Some Examples of the Multicollinearity

When It Comes to Investing

As an investor, you may take into account multicollinearity while using technical analysis to forecast the likely price fluctuations of a stock or commodity futures. Experts in the sector want to avoid utilizing collinear technical signals, meaning that they are dependent on identical or related inputs and hence provide comparable forecasts about the reliant variable of price fluctuations. As a result, independent variables must be used to guarantee that the market is analyzed from a variety of distinct perspectives.

"A fundamental requirement for successfully using technical analysis demands avoiding multicollinearity across indicators," says noted technical analyst and developer of the Bollinger Bands tool John Bollinger. Analysts avoid employing multiple indicators of the same kind to address the issue. It's very uncommon for analysts to do two distinct analyses of the same asset utilizing two different types of indicators, like a momentum predictor and a trend indicator.

For instance, stochastic and RSI use identical inputs and provide comparable outcomes regarding momentum signals. A trend predictor that isn't likely to be substantially associated with a momentum indicator should be included in the mix.

In Biology

There are numerous additional examples of multicollinearity. Human biology is one example of this. Blood pressure, for instance, is not just related to a person's age but also factors such as weight, stress, and even the person's pulse.

With Multicollinearity, What Are The Options?

A model's multicollinearity may be reduced by removing the variables that have been discovered to be particularly collinear. Try to mix or alter the bothersome variables to reduce their association. Modified equations that better cope with multicollinearity, like ridge regression and principal component regression, are available if the first option does not perform or is not feasible.

The Last Thought

There are a number of dangers to be aware of when working with regression models, whether they are already in place or being built from scratch. It may lead to judgments about the null hypotheses argument that aren't supported by the facts. If it's not adequately understood, it can lead to bad professional decisions and wrong findings.

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