Hello,
The "error" is just a warning, these are not the same thing. And the
warning says that you're giving a wrong scope argument, one that
includes the response. See ?add1. Argument 'scope' is "a formula giving
the terms to be considered for adding or dropping." And you're passing
the entire data.frame, not just the regressors.
To get rid of the warning, try the following.
add1(mydata.lm, ~ A + B + C + D, test='F')
Hope this helps,
Rui Barradas
Em 04-01-2013 23:53, dada escreveu:
Hi
I am trying to build a regression model. My data looks like this:
A B C D E
1 1 1 2.57 5
2 0 0 1.64 3
0 5 1 4.8 1
1 3 0 3.56 168
1 1 1 2.13 1
0 3 1 5 168
2 0 0 7.75 28
4 0 2 2.85 168
3 0 1 1.89 6
1 1 1 2.33 3
3 2 2 1.77 168
1 0 0 1.38 0.04
0 6 1 4.57 168
2 2 2 2.86 1
3 1 1 4.11 168
3 0 2 3 84
1 1 1 2.5 56
where E is a response variable and A, B, C, D are predictor variables. Below
are commands which I enter in R:
str (mydata)
mydata.lm = lm (E ~ 1, data = mydata) # to create a blank model
add1(mydata.lm, mydata, test='F') # to add the best predictor variable to
the blank model
However at this point the message appears:
Warning messages:
1: In model.matrix.default(Terms, m, contrasts.arg = object$contrasts) :
the response appeared on the right-hand side and was dropped
2: In model.matrix.default(Terms, m, contrasts.arg = object$contrasts) :
problem with term 4 in model.matrix: no columns are assigned
What does it mean ? Could you please help ?
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