Hi Sim,
To generate the expected counts from a fitted distribution, you can use the probability density function (PDF) of the fitted distribution to generate the expected values for each bin.
Here's an example for the same,
observed_data = exprnd(2, 100, 1);
pd = fitdist(observed_data,'Exponential');
num_bins = 10;
bin_edges = linspace(min(observed_data), max(observed_data), num_bins+1);
expected_values = numel(observed_data) * diff(cdf(pd,bin_edges));
% since the area of the pdf must be 1, it is better to obtain the expected_counts by multiplying with the total number of observations accumulated on every single bin
expected_counts = expected_values * numel(observed_data);
[h, p] = chi2gof(observed_data, 'Expected', expected_counts);
Hope this helps!
