# R-beta: More glm bugs

**Peter Dalgaard BSA
**
p.dalgaard@biostat.ku.dk

*06 Jan 1998 13:21:52 +0100*

Martin Maechler <maechler@stat.math.ethz.ch> writes:
>* The following, I think is more a problem of model.matrix(.) and such lower
*>* level functions which I leave for Thomas and Ross ...
*>*
*>* Jim> 3. The following two lines should produce the same result but don't:
*>* Jim> glm(y~x1:x2:x3-x1:x2:(1+x3))
*>* Jim> glm(y~x1:x2:x3-x1:x2:-x1:x2:x3)
*>* Jim> Only the second gives the correct answer. I have not tried to fix this.
*
There seems to be a typo in Jims 2nd example (extra :) (no, that was
not a smiley...). However, the problem seems to boil down to this:
>* model.matrix(~x1:x2:1)
* (Intercept)
[1,] 1
[2,] 1
[3,] 1
[4,] 1
[5,] 1
[6,] 1
[7,] 1
[8,] 1
attr(,"assign")
[1] 0
Which is pretty clearly wrong. It should be the same as ~x1:x2
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk) FAX: (+45) 35327907
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