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st: RE: Spline Regressions and Log-Log Models

From   "Nick Cox" <>
To   <>
Subject   st: RE: Spline Regressions and Log-Log Models
Date   Wed, 19 May 2010 17:22:13 +0100

I know of no reason why you should not work with splines here. In work
on loosely similar problems with Earth and environmental science data I
would feel free to use splines based on logged variables. The splines
don't know where the variables have been. 


Thad Daniel Calabrese

I've been modeling the relationship between an organization's income and
its accumulated wealth. The existing literature has a fairly standard
log-log model with income as the DV and wealth as one of the IVs. All
variables in the literature are logged.

When I log my wealth variable and graph it against the log of income,
the variable's linearity is certainly improved, but it is obviously not
perfectly straight (nor did I expect it to be).

The question I have is this: could I attempt to improve the model fit
using spline regression? I've only seen splines used on non-transformed
(but normalized) independent variables. I assume there must be a reason
for that and so it concerns me to try with transformed data.

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