R-alpha: glm

Jim Lindsey (jlindsey@luc.ac.be)
Tue, 21 May 1996 10:17:14 +0200 (MET DST)


From: Jim Lindsey <jlindsey@luc.ac.be>
Message-Id: <9605210817.AA12732@alpha.luc.ac.be>
Subject: R-alpha: glm
To: r-testers@stat.math.ethz.ch
Date: Tue, 21 May 1996 10:17:14 +0200 (MET DST)

(1) In 0.6, cmd/pager is not executable - it needs chmod a+x
(2) On my Linux machine, R does not read .First or .Last. Hence I cannot
    set options there.
(3) Here is my quick fix for convergence of saturated models in glm().
    Also trace did not work, so one line for that. Thus, three changes in
    library/base/glm:
(a) before the line
	#check for divergence
     add
if(control$trace)cat("Deviance =",dev,"Iterations =",iter,"\n")
(b) after the line
	#check for convergence
    change to
if(dev==0|(abs((dev-devold)/dev^2)<control$epsilon
	&abs((coef-coefold)/sum(coef^2))<control$epsilon)){
(c) in  print.summary.glm, in the cat() that runs over several lines,
	remove digits,  :
"Residual deviance: ", x$deviance,  #digits,
    This error explains why deviances seemed so small: there was an
extra 4 tacked on the end of the exponent.
(4) I still think the output for contrasts in factor variables is very
    misleading and should be changed. Not only is the numbering wrong
    but, if there are only two levels, R puts no number at all so that
    it is impossible to distinguish it from a continuous variate.
Cheers, Jim
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