Re: reduced major axis regression (RMA) and allometric models using MathProg in GLPK

[Nigel Galloway]

Andrew,

Attached is xyacfs.mod which extends yacfs.mod to permit
investigation of data which may have errors in x (XonY) or y
(YonX). It adds a Weight parameter:

     When set to 1 the model produces best fit by least squares
with all error in y and none in x (YonX);
     When set to zero the model produces best fit by least squares
with all error in x and none in y (XonY);
     When set to 0.5 the model assumes equal error in x and y
producing results similar to fitting by Reduced Major Axis Analysis.

Please add this to the examples section if you think it is uaseful.

Thanks,

Nigel

> ----- Original Message -----
> From: "Noli Sicad" <nsicad@...>
> To: Nigel_Galloway@...
> Subject: reduced major axis regression (RMA) and allometric
> models using MathProg in GLPK
> Date: Fri, 23 Oct 2009 13:49:59 +1100
>
>
> Hi Nigel,
>
> Thanks for sharing your regression i.e. curve fitting examples using
> Mathprog in GLPK (cflsq.mod, qfit.mod and yacfs.mod).
>
> I think you have heard about RMA regression. Would be possible to have
> another example using  reduced major axis regression (RMA) using
> MathProg?
>
> Here are references:
>
> [R] test regression against given slope for reduced major axis
> regression (RMA)
> http://finzi.psych.upenn.edu/R/Rhelp02a/archive/80841.html
>
> RMA http://www.bio.sdsu.edu/pub/andy/RMAmanual.pdf
>
> Thanks in advance.
>
> Regards, Noli

>

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[Andrew Makhorin]

Hi Nigel,

> Attached is xyacfs.mod which extends yacfs.mod to permit
> investigation of data which may have errors in x (XonY) or y
> (YonX).

Thank you for your example. I included it (the recent version) in the
glpk examples subdirectory.


Andrew Makhorin



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