[R] Maximum # of predictors?

[Uwe Ligges]

Jim BRINDLE wrote:

> Hello,
> 
> Is there anyway one can have more than 11 independent variables in a 
> regression model?  To hopefully illustrate: with 13 predictors in my model, 
> the last 2 coefficient estimates are "NA".  When I view the summary, it 
> indicates that 2 coefficients are "not defined because of singularities".  I 
> am using the command:
> 
> mod <- lm(y ~ ., data = volumes[,3:22])
> 
> I am fairly new to R so I don't know if my issue is something inherent to R 
> or my modeling approach.
> 
> Any insight would be most appreciated... Thanks in advance


The question has not much to do with R, but with linear models.
Probably you don't have enough observations in order to estimate those 
coefficients. Please read some statistical textbook on the topic of 
degrees of freedom in linear models and regression analysis.

Uwe Ligges


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