-------- Original Message -------- Subject: Re: question about Regression in MorphoJ Date: Mon, 21 Nov 2011 14:38:37 -0500 From: Chris Klingenberg <[email protected]> Reply-To: [email protected] Organization: University of Manchester To: [email protected] Dear Paola The regression score is computed as the projection of the data points onto the vector of regression coefficient, and a separate one is provided for each independent variable 9if there are two or more). In your example, there is only one independent variable, centroid size. So the regression score (forget about the number 1; there's only one) is the shape variable that is best related to centroid size ("best" linear fit in the sense of the least-squares optimisation used in regression). It is useful to see the trend in the data, check for groupings etc. For more details on the regression score, see Drake, A. G., and C. P. Klingenberg. 2008. The pace of morphological change: historical transformation of skull shape in St. Bernard dogs. Proceedings of the Royal Society of London, B Biological Sciences 275:71–76. PDF at http://www.flywings.org.uk/PDF%20files/ProcRSoc2008.pdf *** The percetage of the Procrustes sums of squares predicted by the regression ("% predicted:" in the text output) is similar to an r-squared value. I hope this helps. Best wishes, Chris On 11/21/2011 7:20 PM, morphmet wrote:
-------- Original Message -------- Subject: question about Regression in MorphoJ Date: Sun, 20 Nov 2011 07:21:59 -0500 From: Paola Nicolosi <[email protected]> Reply-To: Paola Nicolosi <[email protected]> To: [email protected] <[email protected]>, morphomet <[email protected]> Hallo to everybody! I would like to know what is the 'Regression score 1' in the graph shape/size doing a Regression between Procrustes coordinates (Dependent variables) and CS (indipendent variables) when using MorphoJ with 2D data. And also how to obtain the r value to evaluate the regression? Thank you in advance, paola
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