Chi-squared Test for Independence
A test statistic χ² = Σ[(observed - expected)² / expected] testing whether two variables in a contingency table are independent, with degrees of freedom = (rows - 1)(columns - 1).
Real World
A market researcher at Netflix might use a chi-squared test for independence to determine whether viewing genre preference (drama, comedy, documentary) is associated with subscriber age group, using data from thousands of accounts.
Exam Focus
Always calculate degrees of freedom as (rows−1)(columns−1) and check all expected frequencies are at least 5 before proceeding.
How well did you know this?