[R] Help with lm and multiple linear regression? (Plain Text version)

Aaron Barzilai aaron_barzilai at yahoo.com
Fri Dec 28 00:22:12 CET 2007


(Apologies the previous version was sent as rich text)

Hello,
I'm new to R, but I've read the intro to R and successfully connected it to an instance of mysql.  I'm trying to perform multiple linear regression, but I'm having trouble using the lm function.  To start, I have read in a simply y matrix of values(dependent variable) and x matrix of independent variables.  It says both are data frames, but lm is giving me an error that my y variable is a list.

Any suggestions on how to do this?  It's not clear to me what the problem is as they're both data frames.  My actual problem will use a much wider matrix of coefficients, I've only included two for illustration.  

Additionally, I'd actually like to weight the observations.  How would I go about doing that?  I also have that as a separate column vector.

Thanks,
Aaron

Here's my session:
> margin
    margin
1    66.67
2   -58.33
3   100.00
4   -33.33
5   200.00
6   -83.33
7  -100.00
8     0.00
9   100.00
10  -18.18
11  -55.36
12 -125.00
13  -33.33
14 -200.00
15    0.00
16 -100.00
17   75.00
18    0.00
19 -200.00
20   35.71
21  100.00
22   50.00
23  -86.67
24  165.00
> personcoeff
   Person1 Person2
1       -1       1
2       -1       1
3       -1       1
4       -1       1
5       -1       1
6       -1       1
7        0       0
8        0       0
9        0       1
10      -1       1
11      -1       1
12      -1       1
13      -1       1
14      -1       0
15       0       0
16       0       0
17       0       1
18      -1       1
19      -1       1
20      -1       1
21      -1       1
22      -1       1
23      -1       1
24      -1       1
> class(margin)
[1] "data.frame"
> class(personcoeff)
[1] "data.frame"
> lm(margin~personcoeff)
Error in model.frame(formula, rownames, variables, varnames, extras, extranames,  : 
        invalid type (list) for variable 'margin'


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