www.gusucode.com > stats 源码程序 matlab案例代码 > stats/ComputeSampleSizeForSelectedPowerValueExample.m

    %% Compute Sample Size for Selected Power Value

% Copyright 2015 The MathWorks, Inc.


%%
% A company runs a manufacturing process that fills empty bottles with
% 100 mL of liquid. To monitor quality, the company randomly selects
% several bottles and measures the volume of liquid inside.

%%
% Determine the sample size the company must use if it wants to detect a
% difference between 100 mL and 102 mL with a power of 0.80. Assume that
% prior evidence indicates a standard deviation of 5 mL.
nout = sampsizepwr('t',[100 5],102,0.80)

%%
% The company must test 52 bottles to detect the difference between
% a mean volume of 100 mL and 102 mL with a power of 0.80.

%%
% Generate a power curve to visualize how the sample size affects the power
% of the test.
nn = 1:100;
pwrout = sampsizepwr('t',[100 5],102,[],nn);

figure;
plot(nn,pwrout,'b-',nout,0.8,'ro')
title('Power versus Sample Size')
xlabel('Sample Size')
ylabel('Power')