Clinical trials take a long time because they're rigorously controlled, with close attention paid to sampling bias and methodology.

临床试验需要花费很长时间，因为它们处于严格控制之下，必须密切留意取样偏差与方法。

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Much of the research on alcohol's benefit comes from studies that observe people over time rather than from controlled clinical trials, which are more reliable.

认为酒精有益的许多研究结果都是从长期观察的测试者身上得来，并不是随机临床试验的方式，相比起来后者更为可信。

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Take, for example, those 19 million studies on PubMed.Some are gold-standard research: large, randomized, controlled clinical trials or meta-analyses that carefully parse millions of data points.

就拿PubMed上的1900万份研究论文来说，一小部分堪称一流：大型，随机，受控的临床试验和结果的荟萃分析与论文提供的数据相当吻合。

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But randomized controlled clinical trials also are used to prove benefit in big drug studies.

FORBES

Cannon says only to weigh data from controlled clinical trials, which are expensive and are funded mostly from drug companies.

FORBES: In Vioxx's Wake

In June, the British Medical Journal published a major analysis of all the controlled clinical trials that have so far been presented.

FORBES: Magazine Article