How to deal with error "Coefficients: 2 not defined because of singularities" in R for factor variables?

Asked Nov 18 '21 at 10:21

Active Nov 18 '21 at 10:21

Viewed 21 times

I ran multiple linear regression in R. The coefficients for 2 levels of factor variables give me NA values and the message: Coefficients: (2 not defined because of singularities)

Please find the summary of the linear model below: https://i.stack.imgur.com/95y2i.png

Please find my code below:

ols <- lm(Inc_sales ~.-Page_nr, data = train)
summary(ols)

What could be causing this and how can I fix it?

asked Nov 18 '21 at 10:21

Irina Lodich

Check your design matrix for collinearity. – Roland Nov 18 '21 at 11:23
It's easy to search our site for error messages like this and the results tend to be exactly what you need. – whuber Nov 18 '21 at 14:57

How to deal with error "Coefficients: 2 not defined because of singularities" in R for factor variables?

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