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linear regression

Asked by lowcalorie on 12 May 2012
i have a table of data
X = 1,2,3,4,5,6,7,8,9
Y= 4 5 6 9 8 7 4 1 2
how can i plot these points without having a line then using linear regression to find the uncertainty with a 95% confidence interval and plot that?

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2 Answers

Image Analyst
Answer by Image Analyst
on 12 May 2012
 Accepted Answer

% Define sample data.
X = [1,2,3,4,5,6,7,8,9];
Y = [4 5 6 9 8 7 4 1 2];
% Do the plotting:
plot(X, Y, 'bo', 'LineWidth', 3, 'MarkerSize', 15);
grid on;
% Maximize the figure window.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Label the various parts of the plot.
fontSize = 20;
title('lowcalorie Plot', 'FontSize', fontSize);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
coefficients = polyfit(X, Y, 1);
fittedY = polyval(coefficients, X);
hold on;
% Do the plotting:
plot(X, fittedY, 'rs-', 'LineWidth', 3, 'MarkerSize', 15);
legend('Y', 'Fitted Y');

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Answer by Richard Willey on 14 May 2012

Alternatively, if you have the 12a version of Statistics Tbx
X = [1,2,3,4,5,6,7,8,9];
Y = [4 5 6 9 8 7 4 1 2];
myFit = LinearModel.fit(X,Y);
plot(myFit)

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