R help - Sep 2003 - predict for mlm does not work properly

Hello,

I've just fitted a model with multi-responses, and I get an object of class
"lm" "mlm".
My problem is that as soon as I invoke the predict method for a dataframe
"newdata", the methods runs and give me back prediction at the fitting
points but not for newdata.

Does someone has an explanation for this behavior, and some ideas to make
predict.mlm work efficiently.

Thanks in advance

Isabelle Zabalza-Mezghani
IFP-Reservoir Engineering Department
Rueil-Malmaison - France

> From: ZABALZA-MEZGHANI Isabelle 
> 
> Hello,
> 
> I've just fitted a model with multi-responses, and I get an 
> object of class "lm" "mlm". My problem is that as soon
as I
> invoke the predict method for a dataframe "newdata", the 
> methods runs and give me back prediction at the fitting 
> points but not for newdata.
What version of R and on what platform are you doing this?  What were the
commands that you tried?

In R-1.7.1 on WinXPPro, I get:
> df <- data.frame(y1=rnorm(10), y2=rnorm(10), x1=rnorm(10),x2=rnorm(10))
> df2 <- data.frame(y1=rnorm(10), y2=rnorm(10), x1=rnorm(10),x2=rnorm(10))
> try.mlm <- lm(cbind(y1,y2) ~ x1+x2, data=df)
> predict(try.mlm)
            y1          y2
1  -0.84974045 -0.19779627
2  -1.08128909  0.17851648
3   0.23572795  0.23167228
4  -0.65118764  0.09273186
5  -0.06741819  0.10396708
6  -0.88852774 -0.05386359
7  -0.21007585  0.07839343
8  -0.07061706  0.01714900
9  -0.67554077  0.07551119
10 -1.36196165  0.33502943
> predict(try.mlm, df2)
    
              y1            y2
  1  -0.66079093  2.772385e-02
  2  -1.25399169  1.344038e-01
  3  -0.64321234  3.044455e-02
  4   0.29611924 -9.523683e-02
  5  -1.01594522  1.557392e-01
  6  -0.04513806 -1.529740e-01
  7  -0.38954683 -2.780412e-03
  8  -1.21828379 -2.460862e-01
  9  -0.38511937  6.092239e-02
  10 -0.34979146 -9.909837e-05

Seems fine to me.

Andy

 
> Does someone has an explanation for this behavior, and some 
> ideas to make predict.mlm work efficiently.
> 
> Thanks in advance
> 
> Isabelle Zabalza-Mezghani
> IFP-Reservoir Engineering Department
> Rueil-Malmaison - France
> 
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