常見例句雙語例句The reasons there are two main expressions for population and sample" is that one is biased estimator and the other is not."“母體”與“樣本”之所以有兩種表達公式，是因為一個是有偏估計，另一個則不是。We give the approximation formulas of the variance of the sample ratio estimator for a population mean and its asymptotically non-biased estimator in multi-stage sampling.討論多階段抽樣比率估計及其樣本量選擇的問題 ，給出了比率估計抽樣均方誤差的近似公式及其漸近無偏估計的公式 。 返回 biased estimator