(Solved): Need help doing this proof on R-markdown
\( 9.9 \) For the multinomial probability distribution, sh ...
Need help doing this proof on R-markdown
\( 9.9 \) For the multinomial probability distribution, show that \[ \operatorname{Cov}\left(n_{i}, n_{j}\right)=-n p_{i} p_{j} \] [Hint: First show that \( \left.E\left(n_{i} n_{j}\right)=n(n-1) p_{i} p_{j} .\right] \)