基本概念 1、 Sample Statistic(样本统计量 a Any number computed from sample data Arandom variable. Known Example: Average weekly food expenditures for 100 sampled residents Random? Yes! Due to randomness of sample selection 2、 Population Parameter(总体参数) o Any number computed for the entire population A fixed number, Unknown Example: mean weekly food expenditures for all 77, 386 residents ) Do we ever know this? NO >)But we estimate it (with error)一、基本概念 1、Sample Statistic（样本统计量）  Any number computed from sample data ⚫ A random variable. Known Example: Average weekly food expenditures for 100 sampled residents »Random? Yes! Due to randomness of sample selection 2、Population Parameter（总体参数）  Any number computed for the entire population ⚫ A fixed number. Unknown Example: mean weekly food expenditures for all 77,386 residents »Do we ever know this? NO! »But we estimate it (with error)