一些过往学习的记录，均是参考和摘抄了一些网上的资料，无法保证描述的准确性。。。
http://onbiostatistics.blogspot.com/2009/01/data-dredging-vs-data-mining-post-hoc.html
- Ad hoc是指完成final统计分析后，有其他针对于该final报告的额外统计分析需求。
- Post hoc是指在submission后，来自于监管部门的审评意见的额外统计分析需求。
对于以上两种情况，实施相同的处理方式。比如需要额外的变量从，ADS的数据集说明文档（specification）则需要同样被补充。相关文档可以在SAP或者验证计划/报告中作为附件，因此对应的版本必须在文件名以及标题中显示。相关文档也可作为独立文档被保存。
而 Post-hoc 分析，即事后分析，是指在数据收集完毕后，根据数据本身特点额外设定分组，提出研究假设，并进行统计分析。
Post hoc常被称为数据疏浚（data dredging）或数据捕鱼（data fishing），其动机往往是为了得到阳性的结果。因此，事后分析结果一般不被各国药品监管部分接受作为药物有效性的证据。
以下是在临床试验的过程中的注意事项： - 临床试验过程中所有的重大变化都需要记录； - 不鼓励进行Ad-hoc分析（Ad-hoc没有先进行假设再分析，不符合严格的统计学原则，只能作为探索性结论）； - 统计判断需要依据临床试验结果的客观说明和表述。
A post-hoc analysis involves looking at the data after a study has been concluded, and trying to find patterns that were not primary objectives of the study. In other words, all analyses that were not pre-planned and were conducted as 'additional' analyses after completing the experiment are considered to be post-hoc analyses. A post-hoc study is conducted using data that has already been collected. https://www.editage.com/insights/zh-hans/node/7139
While both post-hoc and ad-hoc analysis may be performed based on the data or results we have seen, the ad-hoc analysis typically occurred alongside the project while the post-hoc analysis occurred absolutely after the project or after the unblinding of the study or after the pre-specified analyses results have been reviewed. In this sense, the ad-hoc analysis is better than post-hoc analysis.