点二列相关 Point Biserial Correlation

点二列相关的适用情况Application of point biserial correlation：

1. 一列为正态等距变量

One column is a normal equidistant variable

1. 另一列为二分命名变量

The other column is a dichotomous named variable

1. 常用于试卷的信度分析

Often used in reliability analysis of test papers

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点二列相关的公式Formulas for point biserial correlation：

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r_pb与t的关系r_pb versus t：

其中n₁、n₂分别为两点变量的样本分布。
Where n₁,n₂ are the sample distributions of the two point variables respectively.