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A Greek letter chi raised to the power two, naming a distribution and its test.
Also known as: Chi square, Chi-squared test symbol
χ² names both a probability distribution and the family of tests built on it — most familiarly the test of whether observed counts differ from expected ones. The letter is chi, not the letter x, though it is very often typed as one.
Names the chi-squared distribution and the statistics that follow it, including the goodness-of-fit and independence tests for categorical data.
Contexts: Mathematics
The character is the Greek letter chi, which resembles a Latin x but is a different letter and a different code point. Typing x squared instead is a common and silent error in written work.
A Greek letter chi — two crossing strokes, the descending one curving below the line — followed by a raised numeral two.
Chi is a Greek letter with a curving descender; the multiplication sign is a symmetric cross. In print they are near-identical at small sizes, and word processors substitute one for the other freely.