D3.2.21 (HL)—Chi-squared test
The chi-squared test compares observed and expected genetic results to judge whether differences could be due to chance in inheritance problems.
- Syllabus
- First assessment 2025
- Objective
- D3.2.21
- Level
- HL
Exam analysis
Chance of appearing2%of analysed past papers
Latest appearanceNovember 2021
Most common paperPaper1
Typical marks1–2
Recent exam appearances
November 2021Paper1 ["HL"] · TZ035[ 1 ]D3.2.21 (HL)—Chi-squared test
November 2019Paper2 ["HL"] · TZ02(c)[ 2 ]D3.2.21 (HL)—Chi-squared test
Practice this objective
Coverage 2019–2021 · Updated 16 Jul 2026
Concept essentials
- Chi-squared compares observed counts with expected counts.
- Expected values must come from a stated genetic hypothesis or ratio.
- A larger chi-squared value means a poorer fit to the expected ratio.