Comparing two means

Practicing Statistics Interview Questions in R

Zuzanna Chmielewska

Actuary

Comparing two means

Hypotheses

Two-tailed test: $$ H_0:\text{ }\mu_1 = \mu_2$$ $$ H_1:\text{ }\mu_1 \neq \mu_2$$

where:

$\mu_{1}$ - the first population's mean

$\mu_{2}$ - the second population's mean

Assumptions

The two-sample t-test's assumptions:

• normally distributed underlying data
• random samples
• independent observations
• homogeneity of variances

Assumptions

The two-sample t-test's assumptions:

• normally distributed underlying data
• random sample
• independent observations
• homogeneity of variances - e.g. bartlett.test()

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

Teaching methods

t-test in R

Two-sample t-test

t.test(value ~ group, data = df, var.equal = TRUE)

t-test in R

Two-sample t-test

t.test(value ~ group, data = df, var.equal = TRUE)

Paired t-test

t.test(value ~ group, data = df, paired = TRUE)

Summary

• two-sample t-test
  • hypotheses
  • assumptions
• paired t-test
• t.test() in R

Let's practice!

Practicing Statistics Interview Questions in R