## BERD R Short Course
## Session 4 Homework Key

##1
y1<-rnorm(100)
y2<-rnorm(100,mean=1,sd=sqrt(3))

#(a)
s1<-summary(y1)
v1<-var(y1)
s2<-summary(y2)
v2<-var(y2)

#(b)
var.test(y1,y2)

#(c)
t.test(y1,y2)

##2
y1<-rnorm(100)
y2<-rchisq(100,df=3)

#(a)
cov(y1,y2)
cor(y1,y2)
cor.test(y1,y2)

#(b)
shapiro.test(y1)
shapiro.test(y2)

#(c)
ks.test(y1,y2)

##3
library(MASS)

#(a)
tb<-table(survey$Sex,survey$Smoke)

#(b)
chisq.test(tb)
fisher.test(tb)

##4

#a
pwr.t.test(d=0.2,power=0.8,sig.level=0.05,type="two.sample",alternative="greater")