also: キー
noun
Refers to the Greek letter Χ/χ, used in mathematics, statistics (e.g., chi-squared test), and physics. The reading カイ is standard; キー is a rare alternative influenced by English.
統計学では、カイ二乗検定がよく使われる。
In statistics, the chi-squared test is often used.
この式のχは未知数を表している。
The χ in this formula represents an unknown quantity.
Alternate reading based on English pronunciation; less common in Japanese.
From the Greek letter Χ (chi). The reading カイ reflects the classical Greek pronunciation, while キー is an English-influenced variant.