Statistics notes - Units of analysis
Statistics notes - Units of analysis
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DOI：
10.1136/bmj.314.7098.1874
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发表时间：
1997-06-28
影响因子：
--
通讯作者：
Bland, JM
中科院分区：
文献类型：
--
作者：
Altman, DG;Bland, JM
在临床研究中，关注的焦点几乎总是患者。如果我们进行一项随机试验来比较两种治疗，我们感兴趣的是比较接受每种治疗的患者的结果。在某些情况下，将对同一患者进行多次测量，但关注的焦点仍然是患者。未能认识到这一事实会导致对单个患者进行多次计数，并可能严重扭曲结果。我们在下面解释这个错误。它在医学研究中的频率在安徒生的经典汇编中有整整一章专门讨论它。[1]最简单的情况是，研究人员研究人体解剖学的一部分，可以说是重复的：眼睛、耳朵、手臂等。在另一个极端，可以对一个病人进行很多测量。这些数据经常出现在牙科中，对每颗牙齿甚至每颗牙齿的每一面进行测量，以及在风湿病学中，可以评估每个手指的每个关节的疼痛或活动度。在统计学术语中，患者是抽样单位（或调查单位），因此应该是分析单位。
In clinical studies the focus of interest is almost always the patient. If we carry out a randomised trial to compare two treatments we are interested in comparing the outcomes of patients who received each of the treatments. In some conditions several measurements will be taken on the same patient, but the focus of interest remains the patient. Failure to recognise this fact results in multiple counting of individual patients and can seriously distort the results. We explain this error below. Its frequency in medical research is indicated by the whole chapter devoted to it in Andersen's classic compilation. 1The simplest case is when researchers study a part of the human anatomy which is, so to speak, in duplicate: eyes, ears, arms, etc. At the other extreme very many measurements can be taken on a single patient. Such data arise frequently in dentistry, with measurements made on each tooth, or even each face of each tooth, and in rheumatology, in which pain or mobility may be assessed for each joint of each finger. In statistical terminology the patient is the sampling unit (or unit of investigation) and thus should be the unit of analysis.