Estimate mean amplitude by using histgram for outlier exclusion
and calculate amplitude/mean ratio to find bad channel & trials
amplitude/mean ratio using Median can be also calculated
[xmax, xstd] = vb_get_max_std_ratio(X)
X(t,n) : signal at time t & n-th trial
xstd : mean amplitude excluding outlier
xmax(n): max amplitude for each trial
= max_t (abs(X(t,n)))
2009-08-10 Masa-aki Sato
Copyright (C) 2011, ATR All Rights Reserved.
License : New BSD License(see VBMEG_LICENSE.txt)0001 function [ymax, ystd] = vb_get_max_std_ratio(data) 0002 % Estimate mean amplitude by using histgram for outlier exclusion 0003 % and calculate amplitude/mean ratio to find bad channel & trials 0004 % amplitude/mean ratio using Median can be also calculated 0005 % [xmax, xstd] = vb_get_max_std_ratio(X) 0006 % X(t,n) : signal at time t & n-th trial 0007 % xstd : mean amplitude excluding outlier 0008 % xmax(n): max amplitude for each trial 0009 % = max_t (abs(X(t,n))) 0010 % 0011 % 2009-08-10 Masa-aki Sato 0012 % 0013 % Copyright (C) 2011, ATR All Rights Reserved. 0014 % License : New BSD License(see VBMEG_LICENSE.txt) 0015 0016 [T, Ntry] = size(data); 0017 0018 pmin = 0.05; 0019 pmax = 1 - pmin; 0020 0021 yamp = abs(data); 0022 % Max of each trial 0023 ymax = max(yamp,[],1); % [1 x Ntry] 0024 0025 % exclude outlier 0026 y = sort(yamp(:)); 0027 y = y(1:fix(T*Ntry*pmax)); 0028 0029 ystd = sqrt(mean(y.^2)); 0030 0031 %% Histgram 0032 % Nbin = 200; 0033 % [h , y] = hist(yamp(:),Nbin); 0034 %% probability dencity 0035 % p = h/sum(h); 0036 %% cumurative probability 0037 % psum = cumsum(p); 0038 %% limit the range of mean calculation (exclude outlier) 0039 % imax = find(psum > pmax, 1); 0040 % jx = find(yamp(:) <= y(imax)); 0041 % ystd = sqrt(mean(yamp(jx).^2)); 0042 % 0043 0044 return 0045 %%% END %%%