Additional Exercise 1 for Session 2.

Explore the tools for power calculation available in the R package.
Compare the results obtained in R with those of other standard packages
(Stata, Minitab, SPSS if available, and at least one web interface,
see e.g. http://users.aol.com/johnp71/javastat.html for links), in
the following situations

1. two independent samples, n=15, sigma=1, mean difference=1.
2. two independent proportions, n=50, p1=0.4, p2=0.2
3. 1-way ANOVA, 3 groups, n=15, sigma=1, max. mean difference=1