`stats.mannwhitneyu()`, Ch.21 section 21.6 margin of error, **Ch.12 section 12.2** - for proportions, **Ch.14 section 14.7** marginal probability, **Ch.8 section 8.7** matched pairs, **Ch.16 section 16.4** matplotlib, **Ch.5 section 5.2**, Appendix B section B.3 maximum likelihood estimation, **Ch.2