See MASS4 pp.149-150 (and I don't know of a similarly detailed explanation
elsewhere, although there is a terser account in the White Book).
On Fri, 11 Feb 2005, Sundar Dorai-Raj wrote:
> Hi all,
>
> Perhaps somebody can explain the following behaviour to me.
>
> Take the following data.frame.
>
Hi all,
Perhaps somebody can explain the following behaviour to me.
Take the following data.frame.
z <- expand.grid(X = LETTERS[1:3], Y = letters[1:3])
Now, from ?formula we see:
The '*' operator denotes factor crossing: 'a*b' interpreted as 'a+b+a:b'.
So I would expect the following:
ncol(model.
