卡方检验(Chi-square test/Chi-Square Goodness-of-Fit Test)
卡方检验是一种用途很广的计数资料的假设检验方法。它属于非参数检验的范畴，主要是比较两个及两个以上样本率( 构成比）以及两个分类变量的关联性分析。其根本思想就是在于比较理论频数和实际频数的吻合程度或拟合优度问题。
它在分类资料统计推断中的应用，包括：两个率或两个构成比比较的卡方检验；多个率或多个构成比比较的卡方检验以及分类资料的相关分析等。
Pearson's chi-square (χ2) test is the best-known of several chi-square tests – statistical procedures whose results are evaluated by reference to the chi-square distribution. Its properties were first investigated by Karl Pearson. In contexts where it is important to make a distinction between the test statistic and its distribution, names similar to Pearson Χ-squared test or statistic are used.
