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方差相等预检验后的均值相等检验AI 解读

In testing equality of means of two Normal populations Student's t -test is not generally applicable when the variances of the two populations may be unequal and their ratio is unknown. In the present paper several procedures are considered whereby a preliminary test is performed to ascertain whether or not the variances may be regarded as equal. On the basis of the outcome of this preliminary test one proceeds to test for equality of means. The optimal choice of the level…

方差异质下均值相等检验的小样本表现AI 解读

By using a finite series representation of the distribution of a certain class of statistics, and by utilizing other techniques presented here, two types of statistic are developed for testing the hypothesis of the equality of the means of two normal populations using small sample sizes. One type of statistic, called unilateral, effectively controls the size of the test under variance heterogeneity if it is known a priori that the variance of one specified population is…