[R] model II regression - how do I do it?

[Mark Difford]

Hi Dylan,

>> While this topic is fresh, are there any compelling reasons to use Model
>> II 
>> regression?

The fact that it is the type of regression used in principal component
analysis makes it a compelling method. Compelling reason? It is used to take
account of measurement errors in both y _and_ x. Usually
practioners/analysts would sidestep this by putting what is measured with
least error on the x-axis and regress y on that. For instance, in doing
calibration curves in nutrient analysis where the analyte is measured using
a spec. Then the spec reading goes on x. I can't tell you how often I have
seen analysts put the (usually) inaccurately determined analyte on x and the
spec reading on y.

HTH, Mark.


Dylan Beaudette-2 wrote:
> 
> On Friday 29 August 2008, Mark Difford wrote:
>> Hi Danilo,
>>
>> >> I need to do a model II linear regression, but I could not find out
>> >> how!!
>>
>> The smatr package does so-called model II (major axis) regression.
>>
>> Regards, Mark.
> 
> While this topic is fresh, are there any compelling reasons to use Model
> II 
> regression?
> 
> Cheers,
> 
> Dylan
> 
> -- 
> Dylan Beaudette
> Soil Resource Laboratory
> http://casoilresource.lawr.ucdavis.edu/
> University of California at Davis
> 530.754.7341
> 
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