[R] polr() error message wrt optim() and vmmin

[Anders Schwartz Corr]

Hi,

I'm getting an error message using polr():

Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess, ...) :
         initial value in 'vmmin' is not finite

The outcome variable is ordinal and factored, and the independant variable 
is continuous. I've checked the source code for both polr() and optim() 
and can't find any variable called "vmmin" as referenced in the error 
message.

Any suggestions welcome.

Thanks,

Anders


> summary(data$ordaodb)
    0    1    2    3    4
8228 3505 1755  559 1757
> summary(data$gpconc)
    Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
   0.138   0.280   0.313   0.305   0.332   0.515
> formula<-data$ordaodb~data$gpconc
> propensityordaodb.plr <- polr(formula, method="cauchit")
> propensityordaodb.plr
Call:
polr(formula = formula, method = "cauchit")

Coefficients:
data$gpconc
       8.508

Intercepts:
   0|1   1|2   2|3   3|4
2.651 3.569 4.593 5.304

Residual Deviance: 40009.85
AIC: 40019.85
> summary(propensityordaodb.plr)

Re-fitting to get Hessian

Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess, ...) :
         initial value in 'vmmin' is not finite
>