28.1 Alternative methods for the same result

• Again T test compares two groups - δ is the difference between group means

power.t.test(delta=50., sd=mean(sds), sig.level=0.05, power=0.8, type="two.sample")

## 
##      Two-sample t test power calculation 
## 
##               n = 8.6
##           delta = 50
##              sd = 35
##       sig.level = 0.05
##           power = 0.8
##     alternative = two.sided
## 
## NOTE: n is number in *each* group