Target population: The population to which the investigator wishes to generalize.4

Technical brief: A type of research review (evidence synthesis) intended to provide an early objective description of the state of science related to a new technology (clinical intervention or health care service) for which limited information exists to support definitive conclusions.57 They also provide a possible framework to assess applications and implications of the intervention and describe ongoing research and future research needs.57 Technical briefs funded by the Agency for Healthcare Research and Quality’s Effective Health Care (EHC) Program are developed by Evidence-based Practice Centers.15 The other type of research review produced by the EHC Program are comparative effectiveness (or effectiveness) reviews.15

Tolerability: A patient’s or participant’s ability or willingness to tolerate or accept unpleasant drug-related adverse events without serious or permanent consequences.2

Toxicity: Refers to the quality of being poisonous (e.g., hepatotoxicity).2

Translational research: The process of applying discoveries generated from laboratory, clinical, or population studies into clinical applications.58 There are two components to translational research: 1) The transfer of new understanding of disease mechanisms gained in the laboratory into the development of new methods for diagnosis, therapy, and prevention and their first testing in humans; and 2) The translation of results from clinical studies into everyday clinical practice and health decision making.59 The ultimate aim is to ensure that new treatments and research knowledge actually reach the patients or populations for whom they are intended and are implemented correctly.58

Treatment effect: The amount of change in a condition or symptom resulting from a treatment (compared to not receiving the treatment).6 It is commonly expressed as a risk ratio (relative risk), odds ratio, or risk difference. Also called estimate of effect.

Treatment group: See experimental group.

Treatment persistence: See persistence.

Trial: An experimental study involving humans, commonly called a clinical trial.4

Trim and fill method: A statistical method used to account for publication bias that adjusts a meta-analysis for the impact of missing studies.60

True negative (TN): A test result that is negative in an individual who does not have disease.4

True positive (TP): A test result that is positive in an individual who has the disease.4

Type I error: The error that results if a true null hypothesis is rejected or if a difference is concluded when no difference exists.4 Also called alpha error, false alarm and false positive.

Type II error: The error that results if a false null hypothesis is not rejected or if a difference is not detected when a difference exists.4 Also called beta error, missed opportunity, and false negative.