医学研究中单向有序表的Ridit分析与秩和检验的关系

The relationship between Ridit analysis and rank sum test for one-way ordinal contingency table in medical research

目的探讨单向有序表中有序变量的5种数量化方法及其相互间的关系，以及数量化后所对应的Ridit分析、秩和检验等统计学分析方法在临床研究中应用的比较。方法通过公式推导秩变换评分法（rank_ri）、Ridit评分法（ridit_ri）、连续性校正的Ridit评分法（ridit_rci）、修订的Ridit评分法（riditrmi）和简单评分法等5种方法相互间的区别与联系，以探讨Ridit分析与秩和检验的关系，并应用SAS8．2对临床实例（石韦冲剂治疗慢性气管炎的病型与疗效的关系）进行验证。结果由于文中所讨论的前4种评分方法间存在确定的线性关系rank_fi=Nridit—ri＋1／2=Nridit_rci=（N＋1）ridit_rmi因而基于3种不同Ridit评分法的Ridit分析所得精确X^2统计量是完全相等的，同时它与Kruskal—Wallis H检验也是等价的；基于Ridit评分法（ridit—ri）的传统Ridit分析以1／12作为Ridit值方差的近似值来计算其近似）（2统计量，检验结论相对保守；考虑到Ridit分析具有可以用（0，1）区间内的平均Ridit值和图形清晰地显示多个组的相互大小关系等优点，而且不是Kruskal—WallisH检验所能做到的，故在比较多组之间疗效优劣的临床研究中应提倡使用Ridit分析的精确）（2检验；通过SAS8．2的freq过程中tables语句的得分类型选项（SCORES=）完全可以直接对单向有序表资料作Ridit分析的精确X^2检验。结论Ridit分析的精确x。检验与Kruskal—WallisH检验是完全等价的，在比较多组之间疗效优劣的临床研究中应提倡使用Ridit分析的精确X^2检验。

Objective To explore several numerical methods of ordinal variable in one-way ordinal contingency table and their interrelationship, and to compare corresponding statistical analysis methods such as Ridit analysis and rank sum test. Methods Formula deduction was based on five simplified grading approaches including rank_ri, ridit_ri, ridit_rci, ridit_rmi, and table scores. Practical data set was verified by SAS8.2 in clinical practice （to test the effect of Shiwei solution in treatment for chronic tracheitis）. Results Because of the linear relationship of rank_ri = N ridit_ri ＋ 1/2 = N ridit_rci = （ N ＋ 1 ） ridit_rmi , the exact X^2 values in Ridit analysis based on ridit_ri, ridit_rci and ridit_rmi were completely the same, and they were equivalent to the Kruskal-Wallis H test. Traditional Ridit analysis was based on ridit_ ri, and its corresponding X^2 value calculated with an approximate variance （1/12） was conservative. The exact X^2 test of Ridit analysis should be used when comparing multiple groups in the clinical researches because of its special merits such as distribution of mean ridit value on （ 0,1 ） and clear graph expression . The exact X^2 test of Ridit analysis can be output directly by proc freq of SAS8. 2 with ridit and modridit option （ SCORES = ）. Conclusion The exact X^2 test of Ridit analysis is equivalent to the Kruskal-Wallis H test, and should be used when comparing multiple groups in the clinical researches.