[R] residuals with missing values

[John Fox]

Dear Ivo,

The default na.action is na.omit, which behaves as you describe. Setting
options(na.action="na.exclude"), or specifying the argument
na.action="na.exclude" in the call to lm(), will produce residuals and other
case statistics that have NA for omitted observations. See ?na.exclude and
?lm for details. 

I hope that this helps,
 John

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of ivo welch
> Sent: Sunday, March 28, 2004 11:25 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] residuals with missing values
> 
> 
> hi:  sorry to bother you all again.  I am running a simple 
> lm(y~x+z) regression, in which some of the observations are missing.  
> Unfortunately, the residuals vector from the lm object omits 
> all the missing values, which means that I cannot simply do 
> residual diagnostics (e.g., plot(y,x)).  Would it not make 
> more sense to have the residuals propagate the missing 
> values, so that the residuals are guaranteed to 
> have the same length as the variables?   Alternatively, maybe the 
> residuals() function could do this instead.  But the 
> documentation is not clear:
> 
>      Methods can make use of 'naresid' methods to compensate for the
>      omission of missing values.  The default method does.
> 
> How?  I have figured out how to write my own function to do 
> what I need (using the names of the residuals object), so 
> this is more a "how to properly do this?" question, and/or 
> "suggestion for improved documentation" than it is a 
> desparate need of mine.
>