Nonparametric Test: The Genetics and IVF Institute conducted a clinical trial of its methods for gender selection. When this textbook was written, 172 of 211 babies born to parents using the YSORT method were boys. If the sign test is used, why is it considered to be a "nonparametric" test of a "distribution-free" test?
Basic Skills and Concepts
Independent Samples: Listed below are skull breadths obtained from skulls of Egyptian males from three different epochs (based on data from Ancient Races of the Thebaid, by Thomson and Randall-Maciver). The Kruskall-Wallis test of equal medians requires independent samples. Are the listed samples independent? Why or why not?
4000 BC- 125 129 131 132 132132 134 135 138 138
1850 BC-129 129 134 134 136 137 137 138 136
150 A.D.-128 136 137 137 138 139 141 142 145
Simple Random Samples: If the Kruskal-Wallis test is to be used with the data in the above exercise, the samples should be simple random samples. What is a simple random sample?
Basic Skills and Concepts
Testing for Bias: The last 103 baseball seasons (as of when this textbook was published) ended with 61 World Series wins by American League teams, compared to 42 wins by National League teams. Can the runs test be used to show that the American League is better because disproportionately more World Series contests are won by American League teams?
Statistical Literacy and Critical Thinking
Nonparametric Test: What is a nonparametric test? What is a parametric test?