Measuring Correlation in Ordered Two-Way Contingency Tables
针对只有少数等级的有序数据，常用积矩相关系数可能产生偏差，偏差取决于等级数和变量偏度。本文讨论了多分格相关系数作为此类数据相关性的测量方法。
The product moment correlation coefficient is often used even for ordinal data with only a few scale steps. This procedure may lead to biased results, where the bias depends on the number of scale steps and on the skewnesses of the observed variables. The polychoric correlation coefficient, which is a generalization of the tetrachoric correlation to the general case, is discussed as a possible measure of correlation for this kind of data.