Why this chapter matters
Many real questions involve group comparisons or categorical relationships rather than a single mean or proportion.
What you will learn
- Apply two-sample confidence intervals and tests for means and proportions.
- Use chi-square tests for independence and goodness of fit with expected-count checks.
- Interpret statistically significant differences with careful context language.
Lessons in this chapter
- Two-sample means and proportionsChoose and run two-sample procedures based on variable type and design.
- Chi-square for independenceEvaluate whether two categorical variables are associated.
- Chi-square goodness of fitCompare observed counts to a claimed categorical distribution.
- Practical interpretation of group differencesReport direction, size, and uncertainty of detected differences.
Study task
Use a two-way table of study program by pass status to run a chi-square independence test and summarize what the result supports.
Chapter checkpoint
What is the null hypothesis in a chi-square test of independence?
The two categorical variables are independent in the population.