Statistics Tip of the Week: The Mean of a Chi-Square Distribution is equal to its Degrees of Freedom.
Chi-Square is a Test Statistic; as such, it has a family of Distributions. There is a different Chi-Square Distribution for each value of Degrees of Freedom, df.
Commonly, Degrees of Freedom is the Sample Size minus 1. But this isn't always the case with Chi-Square. That will be covered in a future Tip of the Week.
Here are some examples of how the Chi-Square Distribution varies as df increases. You might observe that the shape of the Chi-Square Distribution is similar to that of the F-Distribution. For more on the Chi-Square, its Distributions and Tests, see the book or this video.
Andrew A. (Andy) Jawlik is the author of the book, Statistics from A to Z -- Confusing Concepts Clarified, published by Wiley.