Testing for a mean with a t-test

Inference for Numerical Data in R

Mine Cetinkaya-Rundel

Associate Professor of the Practice, Duke University

Hypotheses

Let's revisit the High School and Beyond survey data.

Do the data provide convincing evidence of a difference between the average reading and writing scores of students? Use a 5% significance level.

$H_0: \mu_{diff} = 0$, There is no difference between the average reading and writing scores.

$H_A: \mu_{diff} \ne 0$, There is a difference between the average reading and writing scores.

Testing for a mean with a t-test

t.test(hsb2$diff, null = 0, alternative = "two.sided")

Testing for a mean with a t-test

t.test(hsb2$diff, null = 0, alternative = "two.sided")

    One Sample t-test
data:  hsb2$diff
t = -0.86731, df = 199, p-value = 0.3868
alternative hypothesis: true mean is not equal to 0
95 percent confidence interval:
 -1.7841424  0.6941424
sample estimates:
mean of x 
   -0.545

Let's practice!

Inference for Numerical Data in R