Ch. 9 Inferences Based on Two Samples

Sections covered: 9.1, 9.4

9.1 \(z\) Tests and CI’s for a Difference Between Two Population Means

(Cases 1 & 2)

Skip: p. 365 (“Using a Comparison…”) to the end of the section

We will only consider tests in which \(\delta_0 = 0\).

9.4 Inferences Concerning a Difference Between Population Proportions

Skip: p. 394 (“Type II Error Probabilities…”) to the end of the section

R

A/B Testing question from class:

clicks <- c(25, 20)
people <- c(100, 100)
prop.test(clicks, people, correct = FALSE)

## 
##  2-sample test for equality of proportions without continuity correction
## 
## data:  clicks out of people
## X-squared = 0.71685, df = 1, p-value = 0.3972
## alternative hypothesis: two.sided
## 95 percent confidence interval:
##  -0.06553817  0.16553817
## sample estimates:
## prop 1 prop 2 
##   0.25   0.20