Negative correlation, perfect, 556, 557
Neyman, Jerzy, 258
Nonparametric methods, 554–555. See also Paired difference experiments; Sign test; Spearman’s rank correlation coefficient; Wilcoxon rank sum test; Wilcoxon (paired difference) signed rank test
Nonrandom sample, 18. See also Random sample
Nonresponse bias, 14, 15, 18
Normal distribution, 196–206
to approximate binomial probabilities, 220–221
approximating binomial distribution with, 218–221
assessment of, 212–213
determining if data are from approximately, 210
explanation of, 196
properties of, 200, 210
standard, 197
Normal probabilities, making inferences from, 202
Normal probability plot
explanation of, 210
interpretation of, 211–212
Normal random variable, 196–206
finding a probability corresponding to a, 201
standard, 198–201
Normality, descriptive methods for assessing, 209–213
Null hypothesis
explanation of, 308–312
formulation of, 313–316
steps to select, 313
Numerical descriptive measures, 54