function plotConfidenceIntervalRegion(x, y1, y2)
    % draws two lines on a plot and shades the area between those
    % lines to indicate confidence interval.
    hold on 
    
    X_interpolated  = linspace(min(x), max(x), 100);
    Y1_interpolated = interp1(x,y1,X_interpolated);
    Y2_interpolated = interp1(x,y2,X_interpolated);
    
    %Plot the line edges
    %plot(X_interpolated, Y1_interpolated, 'LineWidth', 0.5, 'LineStyle', '--', 'Color', '#FE1A1A');
    %plot(X_interpolated, Y2_interpolated, 'LineWidth', 0.5, 'LineStyle', '--', 'Color', '#FE1A1A');
    
    fill([X_interpolated fliplr(X_interpolated)], [Y1_interpolated fliplr(Y2_interpolated)], [0 71 138] ./ 255, 'EdgeColor', 'none', 'FaceAlpha', 0.2);
    
    hold off
end