R help - Apr 2009 - HELP: Use predict for Tobit Model. How to predict values in Tobit Model???

Hello,

I am working on a Tobit Model for a consumer good, left censored with zero.

Relation: Sales of product depend on price, promotion (dummy), Season(dummy)
and store (dummy)


Used standard Tobitmodel with package(AER) vor a 48 week period:

tobitmodel<-tobit(SALE~Price+Promotion+Season+Store,data= datatobit)

Now I want to predict the values for week 49-52.

Used predict device:

pred<-predict(tobitmodel, newdata=datatobitnew)

I receive negative predicted values for Y! That does not make any sense??

Do I use the device wrong? Is there another way to predict Sales for new
data?

Thank you very much in advance for your help!
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