[Rd] suggested changes to summary.glm and summary.lm (PR#2776)

jfox at mcmaster.ca jfox at mcmaster.ca
Mon Apr 14 14:59:26 MEST 2003

Something for the wish list (not really a bug):

I was reminded of what I see as a problem with summary.glm last week when 
some of my students fell into a trap in a homework exercise, defining a 
logit model in which coefficients were aliased. When this happens in lm, 
summary.lm prints a message ["Coefficients: (1 not defined because of 
singularities)"], but summary.glm is silent. In both instances, the print 
methods show aliased coefficients as NA.

At minimum, I think that it would be desirable for summary.glm to indicate 
that there's a problem. In addition, I would prefer that both summary.glm 
and summary.lm include aliased coefficients (as NA) in the table of 

Thanks for your consideration,
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox

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