在常態分布母體下，當變異數未知且不相等時，Bishop and Dudewicz(1978)提出二階段抽樣程序方法來檢定母體平均數是否相等。二階段抽樣程序是一種屬於實驗設計的方法，其先決定第一階段的初始樣本數，然後在第二階段收集更多的樣本。本文討倫其初始樣本數和最後總樣本數之間的關係。本文另提供兩個指標T和R來幫助選取初始樣本數。 When observations are taken from populations that are normally distributed with unknown and possibly unequal variances, Bishop and Dudewicz (1978) proposed a two-stage sampling procedure for the analysis of variance problem under heteroscedasticity. The procedure is a design-oriented process which requires an initial sample at the first stage and additional observations at the second stage. In this article we discuss the relationship between the initial sample size n_0 and the final total sample size. Two indicators T and R are provided to help selecting the initial sample size.
