R-alpha: graphs and glms

Jim Lindsey (jlindsey@luc.ac.be)
Tue, 28 May 1996 11:04:47 +0200 (MET DST)


From: Jim Lindsey <jlindsey@luc.ac.be>
Message-Id: <9605280904.AA03947@alpha.luc.ac.be>
Subject: R-alpha: graphs and glms
To: r-testers@stat.math.ethz.ch
Date: Tue, 28 May 1996 11:04:47 +0200 (MET DST)

Here are some miscellaneous problems I picked up over the weekend with 0.6:
(1) The problem with PAGER was that Linux sets it to less with the option
    -P followed by the prompt string in double quotes. This is not handled
    properly, the string being broken up at spaces, but it appears to be a
    Linux problem, not R.
(2) typing in, for example trying to assign values to it, gives a syntax error
(3) There is a problem with the W&R notation, both in lm() and glm(). I was
    fitting models to a 2-way contingency table with both variables having
    ordered values. The minimal model, sum of the two factor variable margins,
    and the saturated model, interaction (*) of these two variables, are 
    identical to GLIM. But putting the two factor margins plus a linear
    interaction (x1+x2+lx1:lx2) is wrong. Still a different answer is obtained
    if a new variable (int <- lx1*lx2) is calculated and used (x1+x2+int).
    Neither is the same as GLIM and both are obviously wrong, although they
    should be the same. That was glm() with poisson. The same problem occurs
    with lm()
(4) The way interaction coefficients for factor variables are currently
    displayed is completely unreadable.
(5) There is a problem with the fact that boxplot() has two sets of triple
    dots in the options. If x and y are two variables, boxplot(x,y) puts
    the first value of y as title. boxplot(x,lty=1) gives 2 boxplots,
    the second wrong. boxplot(x,main="title") gives a syntax error.
Jim
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