Results for Additional Exercise 1 for Session 2.

Standard functions in R include
  power.t.test, power.prop.test, power.anova.test

Software included in review: R, Stata, Minitab, UCLA web interfaces.

1. two independent samples, n=15, sigma=1, mean difference=1

Software (function)                                     Value
R: power.t.test(15,1,1)                                 0.7529
Stata: sampsi 0 0, alpha(.05) n1(15) sd1(1) sd2(1)      0.7819
Minitab:                                                0.7529
UCLA:                                                   0.753

2. two independent proportions, n=50, p1=0.4, p2=0.2

Software (function)                                     Value
R: power.t.prop(50,0.4,0.2)                             0.5901
Stata: sampsi 0.2 0.4, alpha(.05) n1(50)                0.5016
Minitab:                                                0.5901
UCLA-arcsine:                                           0.599
UCLA-Fisher's exact:                                    0.502
Russ Lenth:                                             0.6088

3. 1-way ANOVA, 3 groups, n=15, sigma=1, max. mean difference=1

Software (function)                                     Value
R: power.anova.test(3,15,var(c(0,0.5,1)),1)             0.6541
R: power.anova.test(3,15,var(c(0,0,1)),1)               0.7851
Minitab:                                                0.6541
Russ Lenth (SD=0.5)                                     0.6541
Russ Lenth (SD=0.58)                                    0.789