For a Poisson distribution X∼Poisson(λ)X \sim \text{Poisson}(\lambda)X∼Poisson(λ), what is the skewness γ1\gamma_1γ1?
λ\lambdaλ
1λ\frac{1}{\lambda}λ1
1λ\frac{1}{\sqrt{\lambda}}λ1
λ\sqrt{\lambda}λ