The Chi-Square Distribution: Facts About The Chi-Square Distribution 1.4 2008/06/20 11:52:02 GMT-5 2008/07/18 14:39:40.667 GMT-5 Barbara Illowsky illowskybarbara@deanza.edu Susan Dean deansusan@deanza.edu Connexions cnx@cnx.org elementary statistics The curve is nonsymmetrical and skewed to the right. There is a different chi-square curve for each df.

The test statistic for any test is always greater than or equal to zero. When df > 90 , the chi-square curve approximates the normal. For X ~ χ 1000 2 the mean, μ = df = 1000 and the standard deviation, σ = 2 ⋅ 1000 = 44.7 . Therefore, X ~ N ( 1000 , 44.7 ) , approximately. The mean, μ , is located just to the right of the peak.