How to compute Intraclass Correlation Coefficient (ICC ) between two adjacency (functional connectivity) matrices?

Hi,

I have two adjacency matrices (adj.RS1 & adjRS2) computed as an output of functional connectivity analysis of a test-retest dataset from CONN toolbox. I would like to compute and plot the Intraclass Correlation Coefficient (ICC) to assess test-retest reliability between these two adjacency matrices. Could anyone guide how can I conduct the ICC analysis? Matrices are as given below in the screenshots (matrix 1=adjRS1).

Thanks for your help.

Answer 1

[Jacob Mathew]

To compute the ICC between 2 matrices, you can utilise the ICC Add On from the “Add On Explorer” in MATLAB. You can find it in the “Home” tab mentioned as “Add-Ons”.

You can find out more about it in the file exchange link below:

https://www.mathworks.com/matlabcentral/fileexchange/22099-intraclass-correlation-coefficient-icc?s_tid=answers_rc2-2_p5_MLT

A simple demo code demonstrating its usage is as follows:

% Setting Seed 
rng(1);  

% Generate sample data for adjRS1 and adjRS2 
adjRS1 = rand(4, 4, 3); % Random numbers between 0 and 1 
adjRS2 = rand(4, 4, 3); % Different set of random numbers 

% Ensuring the matrices are symmetric and have zeros on the diagonal 
for i = 1:3 % Loop through each subject 
    for j = 1:4 % Loop through each ROI 
        adjRS1(j, j, i) = 0; 
        adjRS2(j, j, i) = 0; 
        for k = j+1:4 
            adjRS1(k, j, i) = adjRS1(j, k, i); 
            adjRS2(k, j, i) = adjRS2(j, k, i); 
        end 
    end 
end 

% Concatenating the data 
combinedData = cat(4, adjRS1, adjRS2); 

% Reshaping it into 2D based on the subjects 
data2D = reshape(combinedData, 4*4, 3*2); 

% Calculating the ICC 
[r, LB, UB, F, df1, df2, p] = ICC(data2D, '1-1') 

The output of the above code is as follows: