Thank you!
But the line you cited was about "response" being a matrix, which is not
our case.
And also I have checked:
Any more thoughts?
Thank you!
> names(tmp)
[1] "School" "Minority" "Sex" "SES" "MathAch" "MEANSES.x"
[7] "Size" "Sector" "PRACAD" "DISCLIM" "HIMINTY" "MEANSES.y"
[13] "Intercept" "y" "X"
> names(MathScores)
[1] "School" "Minority" "Sex" "SES" "MathAch" "MEANSES.x"
[7] "Size" "Sector" "PRACAD" "DISCLIM" "HIMINTY" "MEANSES.y"
> class(tmp)
[1] "data.frame"
> head(tmp)
School Minority Sex SES MathAch MEANSES.x Size Sector PRACAD
1 1224 No Female -1.52800000 5.876 -0.428 842 Public 0.35
2 1224 No Female -0.83155757 19.708 -0.428 842 Public 0.35
3 1224 No Male -0.91452283 20.349 -0.428 842 Public 0.35
4 1224 No Male -1.33600000 8.781 -0.428 842 Public 0.35
5 1224 No Male -0.35329874 17.898 -0.428 842 Public 0.35
6 1224 No Male 0.05388877 4.583 -0.428 842 Public 0.35
DISCLIM HIMINTY MEANSES.y Intercept y X.(Intercept) X.SES
1 1.597 0 -0.428 1.000000 5.87600 1.00000000 -1.52800000
2 1.597 0 -0.428 1.414214 27.87132 1.41421356 -0.83155757
3 1.597 0 -0.428 1.732051 35.24550 1.73205081 -0.91452283
4 1.597 0 -0.428 2.000000 17.56200 2.00000000 -1.33600000
5 1.597 0 -0.428 2.236068 40.02114 2.23606798 -0.35329874
6 1.597 0 -0.428 2.449490 11.22601 2.44948974 0.05388877
X.factor(Sector)Public
1 1.00000000
2 1.41421356
3 1.73205081
4 2.00000000
5 2.23606798
6 2.44948974
On Sat, May 12, 2012 at 6:47 AM, S Ellison <s.elli...@lgcgroup.com> wrote:
> >I am trying to understand why this line works:
> >
> > lm1x = lm(y~X-1, tmp)
>
> Well, I would not normally define a data frame element as a matrix myself
> (though I might well define a list element as one). But specifying a
> matrix as the terms part of an lm is documented in lm's details:
> "If response is a matrix a linear model is fitted separately by
> least-squares to each column of the matrix"
>
> So _something_ will happen.
>
> Whether the something is useful depends on the intent.
>
> > Here it seems that I was combining the design matrix and the data
> frame...
> Did you inspect tmp after adding the design matrix? Was it an odd looking
> data frame or a list?
> What seems to have been done is that the design matrix has been added to a
> list. I wouldn't normally do that if tmp is a data frame, and r would not
> do so unless the lengths all matched. But a list should be ok. And lm
> takes a list or environment as its data argument, so a list of things will
> work even if they are different types. In other words tmp is just a ragbag
> of things, each of which lm understands.
> *******************************************************************
> This email and any attachments are confidential. Any u...{{dropped:11}}
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