Even carefully constructed observational studies that correct for such variables can only find correlations, not prove a cause-and-effect relationship.

即便是那些精心设计、对这些变量已作调整的观察性研究也只能发现其中的相关性，而无法证实一种因果关系。

youdao

Even carefully constructed observational studies that correct for such variables can only find correlations, not prove a cause-and-effect relationship.

即便是那些精心设计、对这些变量已作调整的观察性研究也只能发现其中的相关性，而无法证实一种因果关系。

youdao