[R] lm output

Brecknock, Peter Peter.Brecknock at bp.com
Fri Oct 9 23:45:04 CEST 2009


Thanks very much for the reply. 

If the data fails the underlying assumptions of regression wouldn't it make sense to suppress all the output and not just the slope coefficient?

Incidently, if I run this simple example in Excel it returns the slope as 0. Intuitively, this makes sense to me ... the best estimate of y would be its mean for any value of x.

Kind regards


-----Original Message-----
From: Daniel Malter [mailto:daniel at umd.edu] 
Sent: Friday, October 09, 2009 4:24 PM
To: Brecknock, Peter; r-help at r-project.org
Subject: AW: [R] lm output

That comes out as an NA because X'X is not invertible because it is not full
rank (one row/column is a linear combination of the other(s)). And that
means there is no unique solution to the system.



Therefore, nope, there is now way to make this come out as a zero, because
it fails the very assumptions of regression analysis.


cuncta stricte discussurus

-----Ursprüngliche Nachricht-----
Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
Auftrag von Brecknock, Peter
Gesendet: Friday, October 09, 2009 5:12 PM
An: r-help at r-project.org
Betreff: [R] lm output

Hi All

I am running a linear regression using the lm object.

In the event that my independent variable is the same across all
observations the regression slope is returned as an NA.

For example, if I have the following 


lm = lm(y~x)
produces the following 

(Intercept)            x  
      13           NA  

Other than post-processing the results, is there a way to output the slope
as 0 rather than NA?



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