10.2. Implementing power analysis with the pwr package

The pwr package, developed by Stéphane Champely, implements power analysis as outlined by Cohen (1988). Some of the more important functions are listed in table 10.1. For each function, the user can specify three of the four quantities (sample size, significance level, power, effect size) and the fourth will be calculated.

Table 10.1. pwr package functions

Function	Power calculations for
pwr.2p.test()	Two proportions (equal n)
pwr.2p2n.test()	Two proportions (unequal n)
pwr.anova.test()	Balanced one-way ANOVA
pwr.chisq.test()	Chi-square test
pwr.f2.test()	General linear model
pwr.p.test()	Proportion (one sample)
pwr.r.test()	Correlation
pwr.t.test()	t-tests (one sample, two sample, paired)
pwr.t2n.test()	t-test (two samples with unequal n)