function[] = statistics(exp)
%
% Calculate pairwise TFCE statistics between aggregates
% based on permutation 
% 
%

for a = 1:length(exp.aggregates)
   
    for b = setdiff(1:length(exp.aggregates), a)
        
        %% retreive matrices for aggregates of comparison
        [traces_a time_a] = exp.get_aggregate_data(a);
        [traces_b time_b] = exp.get_aggregate_data(b);
        
        %% TODO:  Check time_a == time_b !
        
        traces = [traces_a ; traces_b];
        labels = [repmat(1, 1:size(traces_a,2)) repmat(2, 1:size(traces_b,2))];
        
        %% calculate true difference:
        
        true_signal = nanmean(traces_a) - nanmean(traces_b);
        
        %% perform permutations
        nperm = exp.settings.Statistics.NumberOfPermutations;
        P = nan(size(traces_1,1), nperm);
        
        for i = 1:nperm
           
            labels_permuted = labels(randperm(length(labels)));
            a_perm = find(labels_permuted==1); b_perm = find(labels_permuted==2);
            
            P(:,i) = nanmean(traces(a_perm,:)) - nanmean(traces(b_perm,:));                        
        end
        hmin = 0; hmax = max(max(P));
        
        %% perform TFCE 
        T = TFCEobj('D', P, 'hmax', hmax);
        T.TFCECalc;
        
        %% store results
        exp.aggregates.statistics.TFCE(a,b).results.pvalues = T.Pvalues;
        %% threshold FWE comparison
        exp.aggregates.statistics.TFCE(a,b).results.pvalues = T.Pvalues;
    end            
end