17_5.py

import random
import pylab
def testSamples(numTrials, sampleSize):
    tightMeans, wideMeans = [], []
    for t in range(numTrials):
        sampleTight, sampleWide = [], []
        for i in range(sampleSize):
            sampleTight.append(random.gauss(0,1))
            sampleWide.append(random.gauss(0,100))
        tightMeans.append(sum(sampleTight)/len(sampleTight))
        wideMeans.append(sum(sampleWide)/len(sampleWide))
    return tightMeans, wideMeans

tightMeans, wideMeans = testSamples(1000, 40)
pylab.plot(wideMeans, 'y*', label = ' SD = 100')
pylab.plot(tightMeans, 'bo', label = 'SD = 1')
pylab.xlabel('Sample Number')
pylab.ylabel('Sample Mean')
pylab.title('Means of Samples of Size ' + str(40))
pylab.legend()

pylab.figure()
pylab.hist(wideMeans, bins=20, label = 'SD = 100')
pylab.title('Distribution of Sample Means')
pylab.xlabel('Sample Means')
pylab.ylabel('Frequency of Occurrence')
pylab.legend()
pylab.show()