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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2000 - INRIA - Carlos Klimann
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
//
function [f,p]=ftest(samples)
//
//Given a number nc of samples each of them composed of nr
//observations this fonction computes in f the Fischer ratio
//(it is the ratio between nr times the variance of the
//means of samples and the mean of the variances of each
//sample). Additionnally it gives (in p) the p-value of the
//computed Fischer ratio. samples is a matrix with type
//nrxnc.
//
//References: Wonacott, T.H. & Wonacott, R.J.; Introductory
//Statistics, J.Wiley & Sons, 1990.
//
[nr nc]=size(samples)
xbar=mean(samples,'r')
xbarbar=mean(xbar)
sx2=sum((xbar-xbarbar).^2)/(nc-1)
sp2=(sum(sum((samples-ones(nr,1)*xbar).^2),'r'))/(nc*(nr-1))
f=(nr*sx2)/sp2
p=1-cdff("PQ",f,(nc-1),(nc*(nr-1)))
endfunction
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