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Absolute risk reduction (ARR): A measure of the change in risk of an experimental treatment in relation to a control treatment. It is calculated by subtracting the experimental event rate from the control event rate.

Accuracy: A measure of how much systematic error is in an assessment or how well a set of measures is centered on the true score.

Active comparator arm: The clinical trial arm in which the participants receive the standard, clinically effective treatment (sometimes identified as the comparison group). One of the five typical treatment arms used in clinical trials.

Administration burden: The time, complexity, work force needed, and cost required to score a questionnaire.

Administration time: The time it takes the client or patient to complete a questionnaire.

Adverse effects: One of a group of five types of questions that can be asked as part of a clinical trial. Adverse effects (side effects) document adverse events encountered during the course of the trial. These types of questions are typically unplanned because adverse advents cannot usually be predicted.

Adverse event: Any injury or otherwise adverse outcome to the health of a participant that happens during a clinical study or within a certain time period after the study is over.

Agent: A factor whose presence, excessive presence, or relative absence is essential for the occurrence of a disease.

Ancillary questions: One of a group of five types of questions that can be asked as part of a clinical trial. Ancillary questions are not specifically planned but can be addressed with the study data. These are often considered substudies within the main study.

Applicability: The relevance of the clinical evidence to the specific client you are treating.

Area under the curve (AUC): An accuracy measure of a clinical test that takes into account all cutoff scores in your investigation and provides the probability that the test result will positively identify a condition.

Attributable risk: The percentage of instances of an illness that can be accounted for by a particular risk factor. Also called attributable fraction.


Bias: A measure of inaccuracy or any effect or interference that produces results that systematically depart from the true value.

Biological gradient: The systematic relationship between a proposed cause and altered rates of disease, injury, or death.

Block randomization: A process of assigning individual subjects to study groups. The researcher divides individual subjects into subgroups called blocks and then randomly assigns individual subjects within each block to treatment conditions.

Boolean operator: A connecting symbol or word, such as AND or OR, that allows a computer user to include or exclude items from a text search.

Boolean search: Performing a text ...

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