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Optimal allocations for two treatment comparisons within the proportional odds cumulative logits model

机译：比例累计累计算法模型中的两个治疗比较的最佳分配

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摘要

This paper studies optimal treatment allocations for two treatment comparisons when the outcome is ordinal and analyzed by a proportional odds cumulative logits model. The variance of the treatment effect estimator is used as optimality criterion. The optimal design is sought so that this variance is minimal for a given total sample size or a given budget, meaning that the power for the test on treatment effect is maximal, or it is sought so that a required power level is achieved at a minimal total sample size or budget. Results are presented for three, five and seven ordered response categories, three treatment effect sizes and a skewed, bell-shaped or polarized distribution of the response probabilities. The optimal proportion subjects in the intervention condition decreases with the number of response categories and the costs for the intervention relative to those for the control. The relation between the optimal proportion and effect size depends on the distribution of the response probabilities. The widely used balanced design is not always the most efficient; its efficiency as compared to the optimal design decreases with increasing cost ratio. The optimal design is highly robust to misspecification of the response probabilities and treatment effect size. The optimal design methodology is illustrated using two pharmaceutical examples. A Shiny app is available to find the optimal treatment allocation, to evaluate the efficiency of the balanced design and to study the relation between budget or sample size and power.
机译：本文研究了两种治疗比较的最佳治疗分配，当结果是序数并通过比例累计累积的算术模型进行分析。处理效果估计器的方差用作最优标准。寻求最佳设计，使得给定的总样本大小或给定预算的这种方差最小，这意味着对处理效果的测试的功率是最大的，或者寻求所需的功率水平以最小的情况实现全部示例大小或预算。结果是三个，五个和七个有序的响应类别，三种治疗效果尺寸和偏斜，钟形或偏振分布的响应概率。干预条件中的最佳比例受试者随着响应类别的数量和相对于控件的那些的干预成本而降低。最佳比例和效果大小之间的关系取决于响应概率的分布。广泛使用的平衡设计并不总是最有效的;与最佳设计相比，其效率随着成本比率的增加而降低。最佳设计对丧失响应概率和治疗效果大小的粉碎非常强大。使用两种药物实施例说明了最佳设计方法。一个闪亮的应用程序可以找到最佳的治疗分配，以评估平衡设计的效率，并研究预算或样品大小与功率之间的关系。

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