[R] diagnostic information in glm. How about N of missing observations?

[Frank E Harrell Jr]

On Thu, 18 Dec 2003 13:27:39 -0600
Paul Johnson <pauljohn at ku.edu> wrote:

> I handed out some results from glm() and the students ask "how many 
> observations were dropped due to missing values"?
> 
> How would I know? 
> 
> In other stat programs, the results will typically include N and the 
> number dropped because of missings.  Without going back to R and 
> fiddling about to find the total number of rows in the dataframe, there 
> is no way to tell.  Somewhat inconvenient. Do you agree?
> 
> -- 
> Paul E. Johnson                       email: pauljohn at ku.edu
> Dept. of Political Science            http://lark.cc.ku.edu/~pauljohn
> 1541 Lilac Lane, Rm 504                              
> University of Kansas                  Office: (785) 864-9086
> Lawrence, Kansas 66044-3177           FAX: (785) 864-5700
>

Fitting functions in the Design package tell you how many observations
were deleted due to each variable in the model.  They generalize the
na.action component stored in the fit object.

Frank 
---
Frank E Harrell Jr   Professor and Chair           School of Medicine
                     Department of Biostatistics   Vanderbilt University