Simple imputation methods were inadequate for missing not at random (MNAR) quality of life data
Simple imputation methods were inadequate for missing not at random (MNAR) quality of life data
复制标题
DOI：
10.1186/1477-7525-6-57
复制
发表时间：
2008-08-04
影响因子：
3.6
通讯作者：
Campbell, Marion K.
中科院分区：
文献类型：
--
作者：
Fielding, Shona;Fayers, Peter M.;Campbell, Marion K.
目的：在随机对照试验(RCT)中常规收集生活质量数据，该试验采用提醒系统，找回了约50%最初丢失的数据。研究的目的是利用这一独特的特征来评估可能的遗漏机制，并评估简单归罪方法的准确性。方法：提醒后作出反应的患者被视为提供了遗漏反应。采用假设检验和Logistic回归方法对失配机制进行评估。结果：假设检验和Logistic回归分析表明，遗漏的数据不是随机的，而是遗漏的。提醒-答复数据显示，在这种情况下，最好的方法是采用简单的归责程序，利用接近归因点收集的信息(最后结转的值、向后结转的下一个值和最后和下一个值)。然而，尽管这些方法是所考虑的简单填补程序中的最好方法，但它们不够准确，不足以确保在填补下获得公正的结果。结论：使用提醒数据可以得出可能的Mnar数据。评估这一机制对于确定归责是否有用很重要。如果很可能出现Mnar，那么简单的推论是不充分的，应该考虑替代战略。
Objective: QoL data were routinely collected in a randomised controlled trial (RCT), which employed a reminder system, retrieving about 50% of data originally missing. The objective was to use this unique feature to evaluate possible missingness mechanisms and to assess the accuracy of simple imputation methods.Methods: Those patients responding after reminder were regarded as providing missing responses. A hypothesis test and a logistic regression approach were used to evaluate the missingness mechanism. Simple imputation procedures were carried out on these missing scores and the results compared to the actual observed scores.Results: The hypothesis test and logistic regression approaches suggested the reminder data were missing not at random (MNAR). Reminder-response data showed that simple imputation procedures utilising information collected close to the point of imputation ( last value carried forward, next value carried backward and last-and-next), were the best methods in this setting. However, although these methods were the best of the simple imputation procedures considered, they were not sufficiently accurate to be confident of obtaining unbiased results under imputation.Conclusion: The use of the reminder data enabled the conclusion of possible MNAR data. Evaluating this mechanism was important in determining if imputation was useful. Simple imputation was shown to be inadequate if MNAR are likely and alternative strategies should be considered.