[R] STEP

[Öhagen Patrik]

Dear All,

I get a strange error message from the STEP Function:

 
> summary(MODELL1<-lm(HEP-HBP~START+ REGION:MH +DUR+AB+ASS+TAS+PRK+OPNEW,na.action=na.exclude))

Call:
lm(formula = HEP - HBP ~ START + REGION:MH + DUR + AB + ASS + 
    TAS + PRK + OPNEW, na.action = na.exclude)

Residuals:
     Min       1Q   Median       3Q      Max 
-4.55426 -1.38241  0.09107  1.15272  4.08577 

Coefficients:
                 Estimate Std. Error t value Pr(>|t|)  
(Intercept)      54.89083  143.18319   0.383   0.7028  
START            -0.02710    0.07362  -0.368   0.7141  
DUR              -0.09959    0.28788  -0.346   0.7306  
AB               -0.20425    0.34256  -0.596   0.5533  
ASS              -0.08205    0.36365  -0.226   0.8223  
TAS              -0.02371    0.04320  -0.549   0.5853  
PRKX             -0.11876    0.76580  -0.155   0.8773  
OPNEWmixed        1.34347    1.65475   0.812   0.4201  
OPNEW100% OP     -0.06336    1.08484  -0.058   0.9536  
REGION:MH        -0.44912    0.20855  -2.154   0.0354 *
REGIONEuropa:MH  -0.28121    0.17509  -1.606   0.1136  
REGIONUSA:MH     -0.20092    0.15425  -1.303   0.1978  
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 

Residual standard error: 2.111 on 59 degrees of freedom
Multiple R-Squared: 0.1753,     Adjusted R-squared: 0.02152 
F-statistic:  1.14 on 11 and 59 DF,  p-value: 0.3482 

> 
> 
> step(MODELL1, direction=c("both"))
Start:  AIC= 116.97 
 HEP - HBP ~ START + REGION:MH + DUR + AB + ASS + TAS + PRK +  
    OPNEW 

Error in lm.fit(x[, jj, drop = FALSE], y, offset = offset) : 
        incompatible dimensions
In addition: Warning message:
longer object length
        is not a multiple of shorter object length in: object$residuals + predict(object) 
> 


What could be the cure?

TIA
Patrik