Assignment5

Q1:

Paired test since correlated:

library(pwr)
power.t.test(n=NULL,delta =.015,sd= 0.03, sig.level=0.05,power=.75,type="paired", alternative = "one.sided")

## 
##      Paired t test power calculation 
## 
##               n = 22.92961
##           delta = 0.015
##              sd = 0.03
##       sig.level = 0.05
##           power = 0.75
##     alternative = one.sided
## 
## NOTE: n is number of *pairs*, sd is std.dev. of *differences* within pairs

n=23 are needed.

Q2:

Since they have different infants allocated into one of two treatments, they are an anology of different people doing different job. We use two sample T-test.

pwr.t.test(n=NULL,d=-0.5,sig.level=0.1,power=.85,type="two.sample", alternative = "less")

## 
##      Two-sample t test power calculation 
## 
##               n = 43.40568
##               d = -0.5
##       sig.level = 0.1
##           power = 0.85
##     alternative = less
## 
## NOTE: n is number in *each* group

n=44 are needed.