the chi-square distribution has only one parameter called the degrees of freedom ( df ). The shape of a chi-square distribution curve is skewed to the right for small df and becomes symmetric(like a normal curve) for large df . The entire chi-square distribution curve lies to the right of the vertical axis and assumes nonnegative values only.
Note: Like all other continuous distribution curves, the total area under a chi-square distribution curve is 1.0; the mean of this distribution is df , its variance equals to 2 df .