dynare/matlab/smirnov.m

72 lines
1.7 KiB
Matlab

function [H,prob,d] = smirnov(x1 , x2 , alpha, iflag )
% Smirnov test for 2 distributions
% [H,prob,d] = smirnov(x1 , x2 , alpha, iflag )
%
% Part of the Sensitivity Analysis Toolbox for DYNARE
%
% Written by Marco Ratto, 2006
% Joint Research Centre, The European Commission,
% (http://eemc.jrc.ec.europa.eu/),
% marco.ratto@jrc.it
%
% Disclaimer: This software is not subject to copyright protection and is in the public domain.
% It is an experimental system. The Joint Research Centre of European Commission
% assumes no responsibility whatsoever for its use by other parties
% and makes no guarantees, expressed or implied, about its quality, reliability, or any other
% characteristic. We would appreciate acknowledgement if the software is used.
% Reference:
% M. Ratto, Global Sensitivity Analysis for Macroeconomic models, MIMEO, 2006.
%
if nargin<3
alpha = 0.05;
end
if nargin<4,
iflag=0;
end
% empirical cdfs.
xmix= [x1;x2];
bin = [-inf ; sort(xmix) ; inf];
ncount1 = histc (x1 , bin);
ncount2 = histc (x2 , bin);
cum1 = cumsum(ncount1)./sum(ncount1);
cum1 = cum1(1:end-1);
cum2 = cumsum(ncount2)./sum(ncount2);
cum2 = cum2(1:end-1);
n1= length(x1);
n2= length(x2);
n = n1*n2 /(n1+n2);
% Compute the d(n1,n2) statistics.
if iflag==0,
d = max(abs(cum1 - cum2));
elseif iflag==-1
d = max(cum2 - cum1);
elseif iflag==1
d = max(cum1 - cum2);
end
%
% Compute P-value check H0 hypothesis
%
lam = max((sqrt(n) + 0.12 + 0.11/sqrt(n)) * d , 0);
if iflag == 0
j = [1:101]';
prob = 2 * sum((-1).^(j-1).*exp(-2*lam*lam*j.^2));
prob=max(prob,0);
prob=min(1,prob);
else
prob = exp(-2*lam*lam);
end
H = (alpha >= prob);