Prev 179964 / 398513 Next

predict function the other way around

David Winsemius

Mon, May 11, 2009 9:29 AM

Why not use the x=T and y=T paramemters and see if :

linearmodel=lm(y~x, x=T, y=T)linearmodel$model
(linearmodel$model)
    y x
1  2 1
2  4 2
3  6 3
4  8 4
5 10 5

.... give you useful results. If you want to interpolate or  
extrapolate, then search for threads regarding those tasks.

David Winsemius
On May 11, 2009, at 11:20 AM, Gerrit Voigt wrote:

> Dear List,
> Consider the following example
>
> x=c(1,2,3,4,5)
> y=c(2,4,6,8,10)
> linearmodel=lm(y~x)
>
> To predict a y-value if you know the corresponding x value is very  
> easy with the command predict.
>
> predict(linearmodel, newdata=(x=1.5))
>
> The other way around, to predict an x-value with a corresponding y- 
> value, doesn't work unfortunately.
> Is there another function that can do that, or do I need to solve  
> that problem the classical way?
>
> Thanks in advance
>
> Gerrit Voigt
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

Thread (2 messages)

Gerrit Voigt predict function the other way around May 11 David Winsemius predict function the other way around May 11