[R] Odp: Help me with prediction in linear model

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 21.07.2010 17:46:02:

> 
> Hi R-community,
> I have the code as follows,i Fitted model as follows
> lbeer<-log(beer_monthly)
> t<-seq(1956,1995.2,length=length(beer_monthly)) #beer_monthly contains 
400+
> entries

not needed
> t2=t^2

> beer_fit_parabola=lm(lbeer~t+t2)

beer_fit_parabola=lm(lbeer~t+I(t^2))

you can use poly(t,2) but coefficients are not directly applicable in 
equation.

> 
> Below is not working for me.
> Please help me in preparing the new data set for the below prediction
> 
> 
> 
> 
predict(beer_fit_parabola,newdata=data.frame(t=seq(1995,1998,length=20),t2=seq
> (1995,1998,length=20))

predict(beer_fit_parabola,newdata=data.frame(t=seq(1995,1998,length=20))

shall be enough
Regards
Petr


> 
> #it is listing all 400+ entries ,but not 20 ahead prediction.
> 
> Thanks In advance for your help
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