Try ``model = FALSE'' rather than ``model = F'' and see if it
makes a
difference. You make have an unwanted variable named ``F'' lurking
somewhere.
(In general it is a *bad* idea to use ``F'' when ``FALSE'' is
intended.)
cheers,
Rolf Turner
rolf at math.unb.ca
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message:
> Hi all,
>
> I got an error message if I set model =F in polr(), like
>
> > polr(y ~ x1 + x2, data1, model = F, method = "probit")
>
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames, :
> variable lengths differ (found for '(model)')
> but
>
> > polr(y ~ x1 + x2, data1, method = "probit")
>
> would work.
>
> Why? Thank you,
>
> Tian