[R] Plot different regression models on one graph

[David Winsemius]

On Feb 13, 2010, at 1:35 PM, Rhonda Reidy wrote:

> The following variables have the following significant relationships  
> (x is the explanatory variable): linear, cubic, exponential,  
> logistic. The linear relationship plots without any trouble.
>
> Cubic is the 'best' model, but it is not plotting as a smooth curve  
> using the following code:
>
> cubic.lm<- lm(y~poly(x,3))

Try:

lines(0:80, predict(cubic.lm, data.frame(x=0:80)),lwd=2)

But I really must say the superiority of that relationship over a  
linear one is far from convincing to my eyes. Seems to be caused by  
one data point. I hope the quotes around "best" mean tha tyou have the  
same qualms.


> lines(x,predict(cubic.lm),lwd=2)
>
> How do I plot the data and the estimated curves for all of these  
> regression models in the same plot?
>
> x <- c(62.5,68.5,0,52,0,52,0,52,23.5,86,0,0,0,0,0,0,0,0,0,0)
>
> y <-  
> c 
> (0.054,0.055,0.017,0.021,0.020,0.028,0.032,0.073,0.076,0.087,0.042,0.042,0.041,0.045,0.021,0.018,0.017,0.018,0.028,0.022 
> )
>
> Thanks in advance.
>
> Rhonda Reidy
>
-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT