Statistics for Business: Decision Making and Analysis, 3rd Edition

... distribution of χ². Under the null hypothesis (and the conditions of this test), the distribution of χ² is known as the chi-squared distribution.

(p. 476 )

A chi-squared distribution looks very different from a normal distribution, though the two are closely related (Behind the Math: Normal and Chi-Squared Distributions). A normal distribution is symmetric around its mean and assigns probabilities to both negative and positive values. In contrast, a chi-squared distribution is right-skewed and assigns probabilities only to positive values. Since χ² sums squared deviations, it can never be negative. Hence, the chi-squared distribution has a lower limit ...