Top of page 9 using Chi^2 to work out E(S^2) and Var (S^2): I'm using 0 to represent sigma. Var [(n-1)S^2/0^2] = 2(n-1). Therefore Var(S^2) = 0^4/(n-1)^2 *2(n-1). Why is 0 raised to 4 (not 2) and why is (n-1) ^2 rather than just (n-1)? In other words why has this equation been multiplied by an extra sigma^2/(n-1)? Is it because it is the second moment? Could you refer me back to the page in the notes which would help me with this please. Cheers