----- Forwarded
message from "F.
James Rohlf"
Date: Mon, 25 Jun
2012 11:53:50 -0400
From: "F. James Rohlf"
Reply-To: ro...@life.bio.sunysb.edu
Subject: RE: problem with RMA regression
To:
morphmet@morphometrics.org
Are your
computations based on nice homogeneous and large sample sizes? For small sample
sizes and messy data there can be large fluctuations in the observed
slopes.
----------------------
F. James Rohlf,
John S. Toll Professor, Stony Brook University
The
much revised 4th editions of Biometry and Statistical Tables are now
available:
http://www.whfreeman.com/Catalog/product/biometry-fourthedition-sokal
http://www.whfreeman.com/Catalog/product/statisticaltables-fourthedition-rohlf
P Please consider the
environment before printing this email
From:
morphmet_modera...@morphometrics.org
[mailto:morphmet_modera...@morphometrics.org]
Sent: Monday, June 25,
2012 6:28 AM
To: morphmet@morphometrics.org
Subject: problem
with RMA regression
----- Forwarded
message from mahdi rabie -----
Date: Mon, 18 Jun 2012 02:41:32
-0400
From: mahdi rabie
Reply-To: mahdi rabie
Subject: problem with
RMA regression
To: "morphmet@morphometrics.org"
Dear
All
I have a problem with RMA
regression (Reduced Major Axis regression) and would be very grateful if
somebody help me.
I'm studying on allometry of
somatic and sexual traits of two Noctuid moths. I want to calculate slope B of
regression line for log transformed data for calculation of kind of allometry
relationship (isometry or negative allometry or positive allometry
).
I first calculated it by OLS
regression and found negative allometry for some sexual traits and isometry and
negative allometry for somatics. Again, I calculated B by method RMA by using
RMA Software. I found isometry for often somatic traits and positive for some of
them and positive allometry for sexual traits ! It is strange results ! as in
literature all authors report negative allometry and isometry for sexual traits.
I don't know my calculations are incorrect ? or software is corrupted ?
or, I found a new phenomenon (positive allometry for sexual
traits)?
Thank
You
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