Definition: A research method in which a group of test subjects is split into two halves -- one group gets a drug that is being studied for effectiveness, and the other gets a placebo. The test subjects do not know whether they've received the real drug or not, and (importantly) those who give the drugs also don't know whether they're giving the real drug or not. This keeps a person who delivers the drug from unintentionally hinting to a test subject about which substance he is receiving. In this way, researchers improve the validity of the test, knowing that any differences between the two groups of test subjects are probably due to the drug, not to any bias in those who give the drug or those who take it.
Pronunciation: pla-SEE-bo
Also Known As: double-blind placebo-controlled study
Alternate Spellings: double blind placebo controlled trial
Examples: While Valerie was encouraged by the new drug's potential shown in a few test cases, she knew that only a double-blind placebo-controlled trial could effectively validate the drug's effectiveness.
