Hi Manuel, your problem is that the new variables you created are of numeric
type, while the model was fitted using factor. So the fix is to convert the
new variables to factors so the type matchs
Luciano


2010/7/7 Manuel Spínola <mspinola10@gmail.com>

> Dear list members,
>
> I am fitting a logistic regression with 5 explanatory factors (which I
> converted to factors):
>
> mod6 = glm(condicion ~ iluminacion + animales + cielo.raso + piso +
> paredes, family=binomial, data=reglog)
>
> I want to obtain the predicted probabilities and the se using the function
> "predict" for some combination of the factors.
>
> iluminacion = 1
> animales = 0
> cielo.raso = 0
> piso = 0
> paredes = 0
>
> newdata1 = data.frame(iluminacion, animales, cielo.raso, piso, paredes)
>
> newdata1$cond = predict(mod6, newdata = newdata1, type="response")
>
> > newdata1$cond = predict(mod6, newdata = newdata1, type="response")
> Aviso en model.frame.default(Terms, newdata, na.action = na.action, xlev =
> object$xlevels) :
>  variable 'iluminacion' is not a factor
> Aviso en model.frame.default(Terms, newdata, na.action = na.action, xlev =
> object$xlevels) :
>  variable 'animales' is not a factor
> Aviso en model.frame.default(Terms, newdata, na.action = na.action, xlev =
> object$xlevels) :
>  variable 'cielo.raso' is not a factor
> Aviso en model.frame.default(Terms, newdata, na.action = na.action, xlev =
> object$xlevels) :
>  variable 'piso' is not a factor
> Aviso en model.frame.default(Terms, newdata, na.action = na.action, xlev =
> object$xlevels) :
>  variable 'paredes' is not a factor
> Error: variables 'iluminacion', 'animales', 'cielo.raso', 'piso', 'paredes'
> were specified with different types from the fit
>
> I don't understand what is wrong.
> Any help will be appreciated.
>
> Best,
>
> Manuel
>
> --
> Manuel Spínola, Ph.D.
> Instituto Internacional en Conservación y Manejo de Vida Silvestre
> Universidad Nacional
> Apartado 1350-3000
> Heredia
> COSTA RICA
> mspinola@una.ac.cr
> mspinola10@gmail.com
> Teléfono: (506) 2277-3598
> Fax: (506) 2237-7036
>
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