Hi all, I'm trying to estimate an ordered probit model using polr: polr(Rating
~ Currac + Debt + Inflation + GDPpc + GDPgr + Ratio + Levelofdev + Eurozone +
Default, method ="probit") where Rating is an ordered discrete dependent
variable and the independent variables are a set of economic determinants (e.g.
inflation rate). However, I keep getting the same error: Error in optim(s0,
fmin, gmin, method = "BFGS", ...) : initial value in 'vmmin' is not finiteI
found it in the C code (src/main/optim.c), at line 523 in the procedure vmmin.
An error is thrown because the result of function fminfn is not finite. In this
function fminfn, at line 82, the result is calculated as result =
REAL(s)[0]/(OS->fnscale). This does not make much sense to me, however. I
understood it should have something to do with a function evaluating at an
infinite value at the starting values. I was hoping someone could explain this
in more detail, or help me overcome the problem. Exluding/omitting NA-valu!
es from the dataset does not resolve the problem. However, when I delete
either Inflation or GDPpc from the set of regressors, it suddenly works fine.
And when I delete everything else but keep both Inflation and GDPpc, it also
still works. If you have experienced the same problem or might know how to deal
with this, I would be really grateful for your response. Thanks a lot, Wouter
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