Curve fitting a percentage of data I have two sets of real data, xdata and ydata, and I'm trying to do an exponencial fitting to them, as shown in my code below. def func(x, a, b, c): return a * np.exp(-b * x) + c popt, pcov = curve_fit(func, xdata, ydata) plt.scatter(xdata, ydata, color='r', label="Demanda máxima", alpha=0.5) plt.plot(xdata, func(xdata, *popt), 'r--') The fitting is working fine, however, I need 90% of my data points to be under/over my fitted curve. Is that a way to do this? Thanks in advice.