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Glossary of Terms

We know that many of the concepts used on this site can be difficult to understand. For that reason, we have provided you with a glossary to help you make sense of the terms used in Comparative Effectiveness Research. Every word that is defined in this glossary should appear highlighted throughout the Web site. When you come upon a highlighted term and would like to read the full definition, you can either click on the word to visit the glossary or roll your mouse over the word for a pop-up definition.

 

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Bias

Definition: Any factor, recognized or not, that distorts the findings of a study. In research studies, bias can influence the observations, results, and conclusions of the study and make them less accurate or believable.

Example:

For example, in studies of new drugs, it often was customary to record adverse events only when they occurred in more than 5 or 10 percent of the people taking the drugs. Since information about rare adverse events was not reported, this led to conclusions that the drugs caused fewer side effects than was actually the case. This led to a bias in the number of reported side effects.

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