A6 Inference: Relationships C->Q

Checking Conditions for the Two-Sample t-test

setwd("/Users/Greg/Documents/Grad School/LAIS 609C/Assignments")
load("lbd1-2.RData")

hist(tv2$time.men, xlab="Amount of TV Time per Week (minutes)", ylab="Number of Men", main="TV Time per Week (Men)")

hist(tv2$time.women, xlab="Amount of TV Time per Week (minutes)", ylab="Number of Women", main="TV Time per Week (Women)")

load("lbd1-4.RData")

hist(tv4$time.men, xlab="Amount of TV Time per Week (minutes)", ylab="Number of Men in Married Couples", main="TV Time per Week (Men in Married Couples)")

hist(tv4$time.women, xlab="Amount of TV Time per Week (minutes)", ylab="Number of Women in Married Couples", main="TV Time per Week (Women in Married Couples)")

Carrying Out the Two-Sample t-test

load("sleep2.RData")

t.test(sleep$undergraduate,sleep$graduate,alternative = "less")

## 
##  Welch Two Sample t-test
## 
## data:  sleep$undergraduate and sleep$graduate
## t = -1.2304, df = 106.33, p-value = 0.1106
## alternative hypothesis: true difference in means is less than 0
## 95 percent confidence interval:
##        -Inf 0.08133355
## sample estimates:
## mean of x mean of y 
##  6.186667  6.420000

Carrying Out the Paired t-test

load("seed.RData")

t.test(seed$regular.seed, seed$kiln.dried.seed, alternative="less", paired=TRUE)

## 
##  Paired t-test
## 
## data:  seed$regular.seed and seed$kiln.dried.seed
## t = -1.6905, df = 10, p-value = 0.06091
## alternative hypothesis: true difference in means is less than 0
## 95 percent confidence interval:
##      -Inf 2.433766
## sample estimates:
## mean of the differences 
##               -33.72727