[R] NA in lm()

[Uwe Ligges]

vinod gullu wrote:
> Hi all,
> I am trying to fit full quadratic model i.e liear +
> square + interaction terms to my data (216 data
> points), so in my case coefficients are 28 (6
> parameters). When i look into summary lm() of model
> all cross terms coefficients are NA. What does this
> mean? Is the regression is not able to solve for these
> coefficients due to some reason.  Or does this mean
> that i should not consider these terms.

Are there any factors with more than 2 levels?
We need some more details...

Uwe Ligges


> Regards,
> 
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