----- Forwarded message from Philipp Mitteröcker <[email protected]> -----
Date: Thu, 28 Nov 2013 11:44:21 -0500
From: Philipp Mitteröcker <[email protected]>
Reply-To: Philipp Mitteröcker <[email protected]>
Subject: Re: sampling size
To: [email protected]
Dear Patrick,
In general, there are no constraints on the number of landmarks.
Only some statistical approaches such as many classification methods, CVA, and
most parametric significance tests require that the sample size is considerably
larger than the number of variables (see, e.g., Mitteroecker & Bookstein 2011).
For classification and CVA, the problem can be circumvented by prior reduction
of the number of variables (e.g., by PCA) or by using other methods (e.g., PCA
or between-group PCA instead of CVA). Parametric significance tests should be
replaced by resampling tests.
Mitteroecker P, Bookstein FL (2011) Classification, linear discrimination, and
the visualization of selection gradients in modern morphometrics. Evolutionary
Biology 38, 100–114
Best,
Philipp
Am 28.11.2013 um 10:59 schrieb [email protected]:
>
> ----- Forwarded message from Patrick Arnold <[email protected]> -----
>
> Date: Tue, 26 Nov 2013 15:53:26 -0500
> From: Patrick Arnold <[email protected]>
> Reply-To: Patrick Arnold <[email protected]>
> Subject: sampling size
> To: [email protected]
>
> Dear all,
>
> I have a very basic question: how many landmarks are suitable for
> certain sample size. I want to examine 60 landmarks of vertebrae. I
> think my sample is too small. Thus, will I need at least 60 vertebrae
> or at least 120, or ....? I do not find a rule or formula for
> calculating sampling size.
> Thanks in advance.
>
> Patrick Arnold
>
> ----------------------------------------------------------------
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>
> ----- End forwarded message -----
>
___________________________________
Dr. Philipp Mitteroecker
Department of Theoretical Biology
University of Vienna
Althanstrasse 14
A-1090 Vienna, Austria
Tel: +43 1 4277 56705
Fax: +43 1 4277 9544
email: [email protected]
homepage: http://theoretical.univie.ac.at/people/mitteroecker
----- End forwarded message -----
