observational study

基本解释

But the authors acknowledged that they could not account for all possible variables, and cautioned that it was an observational study that draws no conclusions about cause and effect.
不过，作者们承认未能一一证明所有可能的变化因素，并提醒这是项观察研究，不能就此得出这两者之间存在因果关系的结论。
We used to think that hormone-replacement therapy reduced the risk of heart attacks by around half, for example, because this was the finding of a small trial, and a large observational study.
例如，我们曾相信激素替代疗法能把心脏病发的风险降低近一半，但是这种疗法大多源于观察性研究，极少基于临床试验。
In June, Northwestern University researchers released the results of the longest observational study ever to investigate the relationship between aerobic fitness and the development of diabetes.
六月，西北大学（Northwestern University）研究人员公布了以往调查有氧健身和糖尿病发病之间关系的最长期观察研究的结果。

Last week, the Lancet published the combined results of a larger observational study, also led by Professor Rothwell.
It was an observational study.

No previous long-term observational study had collected both environmental and biomedical information starting in utero.
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In an observational study like this, however, it is always possible that there is a difference between the women who decided to take hormones and those who had not.
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