Understanding Multicollinearity in Regression Analysis
Multicollinearity in regression analysis can be assessed using various tests such as Variable Inflation Factors (VIF) and R^2 value. VIF measures the strength of correlation between independent variables, while an R^2 value close to 1 indicates high multicollinearity. The Farrar Glauber test and construction of a correlation matrix are also methods to detect multicollinearity in regression models.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
E N D
Presentation Transcript
TESTS TO CHECK MULTICOLLINEARITY Anindita Chakravarty
VIF (Variable Inflation Factors). VIF determines the strength of the correlation between the independent variables. It is predicted by taking a variable and regressing it against every other variable. VIF score of an independent variable represents how well the variable is explained by other independent variables.
R^2 value is determined to find out how well an independent variable is described by the other independent variables. A high value of R^2 means that the variable is highly correlated with the other variables. This is captured by the VIF which is denoted below: VIF= 1 1- R2
So, the closer the R^2 value to 1, the higher the value of VIF and the higher the multicollinearity with the particular independent variable. NOTE: VIF starts at 1 and has no upper limit VIF = 1, no correlation between the independent variable and the other variables VIF exceeding 5 or multicollinearity between this independent variable and the others 10 indicates high
FarrarGlauber test: If the variables are found to be orthogonal, there is no multicollinearity; if orthogonal, then at multicollinearity is present. the variables are not least some degree of The Farrar Glauber test has also been criticized by other researchers
Construction of a correlation matrix Construction of a correlation matrix among the explanatory variables will yield indications as to the likelihood that any given couplet of right-hand- side variables are problems. creating multicollinearity Correlation values (off-diagonal elements) of at least 0.4 are sometimes interpreted as indicating a multicollinearity problem.