www.gusucode.com > stats 源码程序 matlab案例代码 > stats/DiagnosticPlotsExample.m
%% Diagnostic Plots % This example shows how to use diagnostic plots to examine your fit. %% % Load the sample data. % Copyright 2015 The MathWorks, Inc. load carsmall %% % Fit a model of |MPG| as a function of |Cylinders| (nominal) and |Weight| . ds = dataset(Weight,MPG,Cylinders); ds.Cylinders = ordinal(ds.Cylinders); mdl = fitlm(ds,'MPG ~ Cylinders*Weight + Weight^2'); %% % Make a leverage plot of the data and model. plotDiagnostics(mdl) %% % There are a few points with high leverage. But this plot does not reveal % whether the high-leverage points are outliers. %% % Look for points with large Cook's distance. plotDiagnostics(mdl,'cookd') %% % There is one point with large Cook's distance. Identify it and remove it % from the model. You can use the Data Cursor to click the outlier and % identify it, or identify it programmatically. [~,larg] = max(mdl.Diagnostics.CooksDistance); mdl2 = fitlm(ds,'MPG ~ Cylinders*Weight + Weight^2',... 'Exclude',larg);