Cohen P, Cohen J
Arch Gen Psychiatry. 1984 Dec;41(12):1178-82. doi: 10.1001/archpsyc.1984.01790230064010.
There are several diseases, including schizophrenia, alcoholism, and opiate addiction, for which the long-term prognosis is subject to disagreement between clinicians and researchers and also among researchers. Part of this disagreement may be attributable to a difference in the populations they sample. The clinician samples the population currently suffering from the disease (a "prevalence" or census sample), while research samples tend to more nearly represent the population ever contracting the disease (an "incidence" sample). The clinician's sample is biased toward cases of long duration, since the probability that a case will appear in a prevalence sample is proportional to its duration, hence "the clinician's illusion." The statistical mechanism of this bias is illustrated and its consequences detailed. Other sources of sampling bias in clinical and research samples are briefly described and partial remedies are suggested.
有几种疾病，包括精神分裂症、酗酒和阿片类药物成瘾，对于这些疾病，临床医生和研究人员之间以及研究人员之间在长期预后方面存在分歧。这种分歧的部分原因可能是他们所抽样的人群存在差异。临床医生抽取的是当前患有该疾病的人群（“患病率”或普查样本），而研究样本往往更能代表曾经患过该疾病的人群（“发病率”样本）。临床医生的样本偏向于病程较长的病例，因为一个病例出现在患病率样本中的概率与其病程成正比，因此出现了“临床医生的错觉”。文中阐述了这种偏差的统计机制并详细说明了其后果。还简要描述了临床样本和研究样本中其他抽样偏差的来源，并提出了部分补救措施。
