How can I fit a lower tail distribution for the lower 25% of the data?

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I have an array of nearly 1000 data. I want to fit a normal distribution on the lower tail for the lower 25% data. How can i do that?

Accepted Answer

Abolfazl Chaman Motlagh
Abolfazl Chaman Motlagh on 9 Feb 2022
Hi. here's a quick example:
%X = zeros(1000,1); % Create data
X = normrnd(2,1.5,1000,1);
X_sort = sort(X); % sort data by their values
X_first_quarter = X_sort(1:ceil(0.25*numel(X))); % select lower 25 percent
Prob_dist = fitdist(X_first_quarter,'Normal'); % fit normal distribution
figure; hold on;
x_values = -5:0.05:5;
y_values = pdf(Prob_dist,x_values);
legend('probability density function of first quarteer','probability density function of all data','fitted normal distribution')

More Answers (1)

Pawan Kumar
Pawan Kumar on 10 Feb 2022
Thank you so much. It really helped.




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