Let $X _ { 1 } , \cdots \cdots , X _ { n }$

Essay

Let $X _ { 1 } , \cdots \cdots , X _ { n }$ be a random sample from a probability mass function or probability density function f(x). For k = 1,2,3,……, the kth population moment is denoted by __________, while the kth sample moment is __________.