Χχ
MATHEMATICS
- Letter used in special functions.
- Index/variable in some areas.
PROBABILITY
- Chi-square distribution χ².
- Appears in tests and distance measures.
STATISTICS
- χ² tests (goodness-of-fit/independence).
- χ² statistic in contingency tables.
PRONUNCIATION
- Ancient Greek
- sound [kʰ]
- Modern Greek
- χι [çi] · sound [x] (before e/i: [ç])
IN FORMULAS
- χ² = Σ (O − E)² / EThe chi-square statistic: observed against expected counts.See it explained at morrisonkuhlsen.com →
HOW TO WRITE IT — click to copy
lowercase
uppercasesame as the Latin letter: LaTeX has no command for it
DON'T CONFUSE IT
- χ x κ λ χ drops below the baseline and its strokes curve; the Latin x sits on the line.
Note: notations vary between books/fields; these are the most common usages.