[R] Using termplot() with transformations of x

[Peter Dunn]

Hi

>    the two models  are identical because of having the same independent
> variable and dependent variable.they produce different termplot()s because
> of they base on different variables,one is x,the other is logx.see the
> lateral axis.

Sure; this is all obvious from the code and the plots.

But my question is *why* two fundamentally identical models produce different termplot()s?

As the original post asks:  If this is intended, what is the logic? Or am I missing something?

Let me place explain further.

Suppose I try this

m1 <- lm(y~x)
termplot(m1)

and I see that there is a problem.  So I decide to use log(x) as a predictor instead of x; I could do this one of two ways:

logx <- log(x)

m2 <- lm(y~logx)
termplot(m2)

m3 <- lm(y~log(x))
termplot(x3)


In the first case, the new termplot() tells me the model looks good.

In the second case, I output is the same as for termplot(m1) produced, and I don't really learn anything new.  

So the original questions remain: If this is intended, what is the logic? Or am I missing something?

Perhaps I could add: How do I explain and justify this behaviour to someone?

Thanks.

P.



Peter Dunn: Biostatistician (Room T4.12)
School of Health and Sport Science
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