[MORPHMET] model II regression statistics PAST

[Patrick Arnold]

Dear morphometrics,

I am frequently using PAST (paleontological statistics; what a great  
free software) for the analysis of morphometric data (geometric and  
traditional). Now I want to do a reduced major axis regression on  
bivariate data (only one Y for each X). However, I do not found the  
possibility to perform a significance test for the regression (F  
statistics) or for the slope and intercept (t statistics).
It is provided for least square regression (e.g., under polynomial  
option) but not for model II regression. Does anyone know a  
possibility to obtain regression statistics in PAST for model II  
regressions?

Thanks in advance.

Cheers
Patrick


--
Patrick Arnold, M.Sc.

wissenschaftlicher Mitarbeiter und Doktorand
Institut für Spezielle Zoologie und Evolutionsbiologie
mit Phyletischem Museum
Friedrich-Schiller-Universität Jena
Erbertstraße 1
07743 Jena
Germany

Phone:  +49 (0)3641 9-49165
Fax:+49 (0)3641 9-49142
E-mail: patrick.arn...@uni-jena.de

--
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
--- 
You received this message because you are subscribed to the Google Groups "MORPHMET" group.

To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.

RE: [MORPHMET] model II regression statistics PAST

[F. James Rohlf]

I don't know about how to do it in PAST, but note that because the slope of the 
standard major axis "regression" line is just the signed ratio of two standard 
deviations, its square follows the F-distribution if one assumes that the two 
variances are based on random samples from two normally distributed 
populations. Thus a test for a slope = 1 corresponds to a 2-tailed test for the 
equality of variances.  One can easily look up probabilities in an F-table or 
compute confidence limits using standard methods. Note that if the samples are 
across different populations or species, as in many (most?) morphometric 
applications, then these assumptions do not hold.


F. James Rohlf, Distinguished Professor, Emeritus. Ecology & Evolution
Research Professor, Anthropology
Stony Brook University

-Original Message-
From: morphmet@morphometrics.org [mailto:morphmet@morphometrics.org] On Behalf 
Of Patrick Arnold
Sent: Saturday, March 12, 2016 4:49 AM
To: morphmet@morphometrics.org
Subject: [MORPHMET] model II regression statistics PAST

Dear morphometrics,

I am frequently using PAST (paleontological statistics; what a great free 
software) for the analysis of morphometric data (geometric and traditional). 
Now I want to do a reduced major axis regression on bivariate data (only one Y 
for each X). However, I do not found the possibility to perform a significance 
test for the regression (F
statistics) or for the slope and intercept (t statistics).
It is provided for least square regression (e.g., under polynomial
option) but not for model II regression. Does anyone know a possibility to 
obtain regression statistics in PAST for model II regressions?
Thanks in advance.

Cheers
Patrick


--
Patrick Arnold, M.Sc.

wissenschaftlicher Mitarbeiter und Doktorand Institut für Spezielle Zoologie 
und Evolutionsbiologie mit Phyletischem Museum Friedrich-Schiller-Universität 
Jena Erbertstraße 1
07743 Jena
Germany

Phone:  +49 (0)3641 9-49165
Fax:+49 (0)3641 9-49142
E-mail: patrick.arn...@uni-jena.de

--
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
---
You received this message because you are subscribed to the Google Groups 
"MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.


-- 
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
--- 
You received this message because you are subscribed to the Google Groups 
"MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.

[MORPHMET] Using photographs from distinct sources to GM analyses

[Pablo Fisichella]

Dear Morphometricians

I am new in geometric morphometrics. I have a question perhaps quite simple
with regards to 2D GM. I am comparing the size/shape of human skulls from
different sources using photographs taken in norma lateralis. One part was
obtained through a standardized protocol while the other part was obtained
from published pictures (with permissions) which were obtained using
different protocols. I have traditional measurements for each skull for the
published data set in order to compute the centroid size. However, taking
into account some theoretical issues I feel that such comparison may be
biased especially regarding size (i.e. CS) because both sets of images were
obtained using different distances between the camera and the target. In
order to minimize the size bias I plan to digitize landmarks and
semilandmarks only along the skull contour given that its shape can be
optimally characterized using a 2D approach. The location of landmarks in
other structures poorly characterized from the 2D approach (i.e distinct to
the contour) would increase the size bias. I will do a procrustes analysis
using both data sets and through a multivariate regression of size on the
procustes coordinates I will obtain residuals (i.e. shape variables). To my
knowledge using this approach I will minimize the size bias mentioned.
Obviously I will not use the centroid size in any subsequent analysis, only
the shape variables. Does anyone tell me if this approach is right? Some
suggestions?
thanks in advance

cheers
Pablo


Este correo electrónico se ha enviado desde un equipo libre de virus y
protegido por Avast.
www.avast.com

<#1979225450_DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

-- 
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
--- 
You received this message because you are subscribed to the Google Groups 
"MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.

Re: [MORPHMET] model II regression statistics PAST

[N. MacLeod]

I can’t help you with PAST, but this reference will allow you to compute the 
correct statistics for a standardized major axis (often erroneously called a 
reduced major axis) regression.

Warton, D. I., et al., 2006, Bivariate line-fitting methods for allometry: 
Biological Reviews, v. 81, no. 2, p. 259–291.

Norm MacLeod



> On 12 Mar 2016, at 14:49, Patrick Arnold  wrote:
> 
> Dear morphometrics,
> 
> I am frequently using PAST (paleontological statistics; what a great free 
> software) for the analysis of morphometric data (geometric and traditional). 
> Now I want to do a reduced major axis regression on bivariate data (only one 
> Y for each X). However, I do not found the possibility to perform a 
> significance test for the regression (F statistics) or for the slope and 
> intercept (t statistics).
> It is provided for least square regression (e.g., under polynomial option) 
> but not for model II regression. Does anyone know a possibility to obtain 
> regression statistics in PAST for model II regressions?
> Thanks in advance.
> 
> Cheers
> Patrick
> 
> 
> -- 
> Patrick Arnold, M.Sc.
> 
> wissenschaftlicher Mitarbeiter und Doktorand
> Institut für Spezielle Zoologie und Evolutionsbiologie
> mit Phyletischem Museum
> Friedrich-Schiller-Universität Jena
> Erbertstraße 1
> 07743 Jena
> Germany
> 
> Phone:  +49 (0)3641 9-49165
> Fax:+49 (0)3641 9-49142
> E-mail: patrick.arn...@uni-jena.de
> 
> -- 
> MORPHMET may be accessed via its webpage at http://www.morphometrics.org
> ---You received this message because you are subscribed to the Google Groups 
> "MORPHMET" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to morphmet+unsubscr...@morphometrics.org.
> 

_

Professor Norman MacLeod
Dean of Postgraduate Education and Training
The Natural History Museum, Cromwell Road, London, SW7 5BD
(0)207 942-5204 (Office Landline)
(0)785 017-1787 (Mobile)
http://www.nhm.ac.uk/hosted_sites/paleonet/MacLeod/

Department of Earth Sciences, University College
London, Gower Street, London WC1E 6BT, UK

Nanjing Institute of Geology & Palaeontology,
Chinese Academy of Sciences, 39 Beijing, Donglu, Nanjing, China
_








-- 
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
--- 
You received this message because you are subscribed to the Google Groups 
"MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.

Re: [MORPHMET] model II regression statistics PAST

[Mauro Cavalcanti]

Patrick,

PAST is "free" as in "free beer", not as in *free speech*. It is gratis,
but not open. The problem you have is just typical of such black box
approach to scientific software development -- since one cannot see the
source code, it is not possible to check how this or that algorithm is
implemented.

Stick to R, where nothing is hidden.

Best regards,

2016-03-12 11:49 GMT-03:00 Patrick Arnold :

> Dear morphometrics,
>
> I am frequently using PAST (paleontological statistics; what a great free
> software) for the analysis of morphometric data (geometric and
> traditional). Now I want to do a reduced major axis regression on bivariate
> data (only one Y for each X). However, I do not found the possibility to
> perform a significance test for the regression (F statistics) or for the
> slope and intercept (t statistics).
> It is provided for least square regression (e.g., under polynomial option)
> but not for model II regression. Does anyone know a possibility to obtain
> regression statistics in PAST for model II regressions?
> Thanks in advance.
>
> Cheers
> Patrick
>
>
> --
> Patrick Arnold, M.Sc.
>
> wissenschaftlicher Mitarbeiter und Doktorand
> Institut für Spezielle Zoologie und Evolutionsbiologie
> mit Phyletischem Museum
> Friedrich-Schiller-Universität Jena
> Erbertstraße 1
> 07743 Jena
> Germany
>
> Phone:  +49 (0)3641 9-49165
> Fax:+49 (0)3641 9-49142
> E-mail: patrick.arn...@uni-jena.de
>
> --
> MORPHMET may be accessed via its webpage at http://www.morphometrics.org
> ---You received this message because you are subscribed to the Google
> Groups "MORPHMET" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to morphmet+unsubscr...@morphometrics.org.
>
>


-- 
Dr. Mauro J. Cavalcanti
E-mail: mauro...@gmail.com
Web: http://sites.google.com/site/maurobio

-- 
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
--- 
You received this message because you are subscribed to the Google Groups 
"MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.