Box Tidwell / Error Message

John Fox

Fri, Dec 1, 2006 6:06 AM

Dear Simon,

It's hard to tell without the data and more information about the nature of
the variables, but I suspect that the program is running into numerical
difficulties because of a flat likelihood at the maximum. Is age2 by any
chance age^2? How is year (in either form) related to age?

I hope this helps,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
--------------------------------

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch 
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Simon P. Kempf
Sent: Friday, December 01, 2006 3:30 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Box Tidwell / Error Message

Dear R-Users,

 

I used the box.tidwell () function of the car Package. 

 

When I used the following formula:

 

semi.sub.in.mi1.boxtidwell_h<-box.tidwell(RENT_LG ~ 
I(age+1)+I(age2+1)+X06A
+ I(X08B+1) + I(X22+1) + I(X24+1) + X31A, ~B_YEAR + C_X01 + C_X14 + 
+ C_X19 +
C_X29A +C_X21 + C_X23 + D_X12 + D_X17 + D_X18 + D_X25 + D_X27 
+ D_X30 +
D_X32 + D_X35, data = semi.sub.in.mi1)

 

everything is fine.

 

However, when I replaced the time dummy variable:

 

semi.sub.in.mi1.boxtidwell_h<-box.tidwell(RENT_LG ~ 
I(age+1)+I(age2+1)+X06A
+ I(X08B+1) + I(X22+1) + I(X24+1) + X31A, ~B_HALF + C_X01 + C_X14 + 
+ C_X19 +
C_X29A +C_X21 + C_X23 + D_X12 + D_X17 + D_X18 + D_X25 + D_X27 
+ D_X30 +
D_X32 + D_X35, data = semi.sub.in.mi1)

 

I get the following error message:

 

Error in lm.fit(x, y, offset = offset, singular.ok = 
singular.ok, ...) : 

        NA/NaN/Inf in foreign function call (arg 1)

 

When I use the following formula (I deleted the I(age2+1) term):

 

semi.sub.in.mi1.boxtidwell_h<-box.tidwell(RENT_LG ~ I(age+1)+X06A +
I(X08B+1) + I(X22+1) + I(X24+1) + X31A, ~B_HALF + C_X01 + 
C_X14 + C_X19 + C_X29A +C_X21 + C_X23 + D_X12 + D_X17 + D_X18 
+ D_X25 + D_X27 + D_X30 +
D_X32 + D_X35, data = semi.sub.in.mi1)

 

It works.

 

Some background information:

 

-          The formula with the predictors to be transformed 
contains only
variables which are >0.

-          The data set does not have any missing values

-          B_YEAR is a factor with 10 levels

-          B_HALF is a factor with 20 levels

-          The data set contains more than 19000 observations.

 

Now, I am bit confused. Why does the function works when I 
use B_YEAR respecitvely why does it work with B_HALF when I 
delete I(age2+1)

 

Thanks in advance,

 

Simon

 

 

 

 

Simon P. Kempf 

Dipl.-Kfm. MScRE Immobilienvkonom (ebs)

Wissenschaftlicher Assistent

 

B|ro:

IREBS Immobilienakademie

c/o ebs Immobilienakademie GmbH

Berliner Str. 26a

13507 Berlin

 

Privat:

Dunckerstra_e 60

10439 Berlin

 

Mobil: 0176 7002 6687

Email:  <mailto:simon.kempf at web.de> simon.kempf at web.de

 


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Box Tidwell / Error Message

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