R-alpha: glm and nlm

Jim Lindsey (jlindsey@luc.ac.be)
Mon, 18 Nov 1996 09:44:51 +0100 (MET)


From: Jim Lindsey <jlindsey@luc.ac.be>
Message-Id: <9611180844.AA29233@alpha.luc.ac.be>
Subject: R-alpha: glm and nlm
To: r-testers@stat.math.ethz.ch
Date: Mon, 18 Nov 1996 09:44:51 +0100 (MET)

1.Set
  a <- y~x
  b <- y~z
  d <- c(a,b)
  Why is is.language(a) true but is.language(d[1]) false? I need this
  or a list for programs that have several regressions in the same
  model, e.g. for mean and variance.
2.If z is an lm with formula say y~x1+x2+x3+x4, update(z,~-x4) is
  accepted but always gives the null model.
3.anova() applied to a glm gives an error, something like NA instead
  of logical in if(np>1)  (from memory, sorry)
4.When I fit models interactively using nlm, I (almost always?) get
  exactly the same results, but when I run the same code in batch, the
  results are generally somewhat different. The optimum can be either
  slightly better or worse.
5.Can someone tell me how to stop R from automatically saving .RData
  in batch mode using a file that will still work correctly when sourced in
  interactive mode? This is driving me mad because I keep destroying my
  carefully designed environment that only contains R functions and
  not data by forgetting and running a file as batch in the same
  directory. Hence, I still disagree strongly with Robert's believe that
  it is natural to save the environment by default in batch mode.
Jim
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