醫(yī)學的最大進展之一，是20世紀50 年代中期采用的一種新研究技術，叫做“臨床對照試驗”，用來確定新藥和其他治療是否安全有效。

One of the greatest advances in medicine was the introduction of a new research technique in the mid-1950s called the controlled clinical trial, which is used to determine if new drugs and other treatments are safe and effective. 

在臨床對照試驗中，一組病人，即治療組，接受新藥或新的療法。另一組病人，即對照組，服用無藥性的丸劑（安慰劑），或接受標準的治療。

In the controlled clinical trial, one group of patients, the treatment group, receives the new drug or new treatment. Another group, the control group, is given an inactive pill (a placebo) or the best standard treatment. 

研究人員然后對經(jīng)過一個時期治療的兩組病人作比較，用嚴格的統(tǒng)計技術對收集的數(shù)據(jù)做分析，以確定新的療法是否比標準療法或不治療更安全有效。

Researchers then compare the two groups after a period of treatment and analyze the data collected  through rigorous statistical techniques to determine whether the new treatment is safer and more effective than standard therapy or no treatment.

多數(shù)臨床試驗在單盲或雙盲基礎上進行。在單盲試驗中，病人不知道他們接受的是新藥還是安慰劑。在雙盲試驗中，病人和醫(yī)生都不知道哪位病人在接受新的治療。

Most clinical trials are conducted on a blind or double-blind basis. In a blind trial, patients do not know whether they receive the new drug or a placebo. In a double-blind trial, neither patients nor physicians know who is receiving the new treatment. 

這一保密是重要的，因為病人如果知道自己在用一種強力的新藥，會期望感到病情好轉(zhuǎn)，并向醫(yī)生報告。

This secrecy is important because patients who know they are taking a powerful new drug may expect to feel better and report improvement to doctors. 

研究人員如果知道一個病人在接受試驗的新療法，也可能會看到病人情況改善，而實際上并無改善。

Researchers who know that a patient is receiving the test treatment may also see improvements that really do not exist.

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