`stats.levene()`, Ch.20 section 20.9 library (Python), **Ch.3 section 3.4** likelihood ratio, **Ch.9 section 9.13** Likert scale, Ch.2 section 2.3 LINE conditions (regression), Ch.22 section 22.16 linear relationship, **Ch.22 section 22.3** `linregress()`, Ch.22 section 22.11 listwise deletion, Ch.7