viii CONTENTS 



5.4 Testing the hypothesis that two random samples came from 



the same binomial population 136 



5.5 The x 2- test when more than one degree of freedom is re- 



quired 140 



5.6 Control charts 146 



Review problems 150 



6. Introductory Sampling Theory for a Normal Population In- 

 volving Only One Variable 153 



6.1 Obtaining the sample 153 



6.2 The statistical distribution of sample means, x i} drawn from 



a normal population 154 



6.3 Estimation of the unknown mean and variance of a popula- 



tion from the information contained in a sample 159 



6.4 A statistical test of a hypothesis that a given sample came 



from a normal population with a specified mean 170 



6.5 A statistical test of the hypothesis that two samples of ob- 



servations have been drawn from the same normal popula- 

 tion of numerical measurements 176 



6.6 Use of the sample range instead of the standard deviation in 



certain tests of statistical hypotheses 182 



6.7 The central limit theorem and non-normal populations . . . 185 

 Review problems 190 



7. Linear Regression and Correlation 192 



7.1 Scatter diagrams and types of trend lines 194 



7.2 A method for determining linear regression (or trend) lines . 198 



7.3 Measurement of the variation about a linear trend line deter- 



mined by the method of least squares 208 



7.4 Coefficients of linear correlation 216 



7.5 Rank correlation 226 



Review problems 230 



Tables 243 



Index 259 



