Hi all Two queries about the E[] operator: 1) In CT3-04 solution 4.8, how is E[X(X-1)] calculated? 2) The notes elsewhere refer to arithmetic using the E[] operator, but I could not find these anywhere. What are the properties of the E[] operator? Thanks
With any expectation we calculate it by multiplying what is in the bracket (in this case X(X-1)) by the probability. So for the Poisson we have: \(E(X(X-1)) = 0*(-1)*P(X=0) + 1*0*P(X=1) + 2*1*P(X=2) + 3*2*P(X=3) + ...\) Ch3 Section 3.3 Ch6 Section 3.2
