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

Effect Size

The amount of change in a condition or symptom because of a treatment (compared to not receiving the treatment). It is commonly expressed as a risk ratio (relative risk), odds ratio, or difference in risk. detail

Effective Dose

The amount of a drug most people need to take to control a disease or the symptoms of a disease. A dose lower than the effective dose would not bring about the outcome (such as relieving symptoms). detail

Effectiveness

Whether a drug or other treatment works in real life. Effectiveness studies of drugs look at whether they work when they are used the way that most people take them. Effectiveness means that most people who have the disease would improve if they used the treatment. detail

Efficacy

Whether a drug or other treatment works under the best possible conditions. In a research study about efficacy, the study participants are carefully selected, and the researchers can make sure the drug is taken properly and stored properly. The study participants may differ from other people in the general public who have the disease. A treatment that has efficacy under the best conditions may not work as well in a different group of people with the same disease. detail

Epidemiology

The field of science that studies the factors causing diseases, illnesses, or injuries in populations or community groups. detail

Evidence Table

A summary of the most important information from a group of research studies. An evidence table can include information on the number of participants in the research trials and the type and frequency of adverse events that participants had while taking the drugs being studied. detail

Evidence-Based Practice

Applying the best available research results (evidence) when making decisions about health care. Health care professionals who perform evidence-based practice use research evidence along with clinical expertise and patient preferences. Systematic reviews (summaries of health care research results) provide information that aids in the process of evidence-based practice. detail

Exclusion Criteria

The criteria, or standards, set out before a study or review. Exclusion criteria are used to determine whether a person should participate in a research study or whether an individual study should be excluded in a systematic review. Exclusion criteria may include age, previous treatments, and other medical conditions. Criteria help identify suitable participants. detail

External Validity

The extent to which clinical research studies apply to broader populations. A research study has external validity if its results can be generalized to the larger population. detail