Experiments and Observational Studies
Experiments and Observational Studies
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实验和观察研究
DOI：
10.1007/978-0-387-73251-0_7
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
N. Longford
中科院分区：
文献类型：
--
作者：
N. Longford
实验和观察研究是统计调查的两种。实验的特点是严格控制所涉及的过程。他们往往会在每个主题（单位）上花费较高的支出，但有更大的潜力在相对较小的样本中收集更多信息。相比之下，观察性研究涉及的控制要少得多，其单位费用往往较低，但推断更困难，并且有些困难无法通过增加样本量来解决。在许多情况下，实验是不可行的，推论必须基于观察研究。他们的分析比实验更具挑战性，并且常常必须依赖于一些无法验证的假设。本章提出了一个框架，其中实验和观察研究只是“研究”，其区别在于设计者对单元处理分配的控制是否存在或一般水平。在几个方面，这种方法与第 3 章中介绍的抽样理论相似。特别是，它利用了推理任务的缺失数据公式。
Experiments and observational studies are two kinds of statistical investigations. Experiments are characterised by tight control over the processes involved. They tend to incur high expenditure per subject (unit), but have greater potential to collect more information in relatively small samples. In contrast, observational studies involve much less control, their expense per unit tends to be lower, but inferences are more difficult to make, and some of the difficulties could not be resolved by increasing the sample size. In many settings, experiments are not feasible, and inferences have to be based on observational studies. Their analysis is more challenging than that of experiments and often has to rely on some unverifiable assumptions.This chapter presents a framework in which experiments and observational studies are simply ‘studies’ distinguished by the presence or absence, or in general the level, of the designer’s control over the assignment of treatments to units. In several aspects, this approach parallels the sampling theory introduced in Chapter 3. In particular, it makes use of a missing-data formulation of the inferential task.