Browse the glossary:
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p-value
— The probability (ranging from 0 to 1) that the results observed in a study could have occurred by the play of chance; … (read more)
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paired study design for diagnostic tests
(diagnostic paired design)
— A study design where two screening or diagnostic tests are compared and all patients receive both an index test and a reference standard test; … (read more)
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parallel group study
— A type of study in which two or more groups of participants receive different treatments at the same time; … (read more)
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participants see study participants
(subjects*, participants)
— The people included in a study; … (read more)
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peer review
— An editorial process for assessing the quality and importance of research reports submitted for possible publication; … (read more)
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performance bias
— Bias resulting from differences in the care provided to the participants in a study, other than the treatments being compared.; … (read more)
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perspective
(analytic perspective, viewpoint)
— In guideline recommendations or economic evaluations, the viewpoint that is adopted, which determines the factors (e.g. costs, effects, acceptability) that are included; … (read more)
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phase 1 trial
— A research study designed to find out how a new drug is dealt with by the body, how the people given it react to it, and the lowest dose that may be effective; … (read more)
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phase 2 trial
— A study designed to find out whether a new drug is promising, to identify common side effects, and refine the dose and duration of treatment; … (read more)
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phase 3 trial
— A study designed to find out whether a promising new drug actually has important beneficial effects and an acceptable frequency and severity of side effects; … (read more)
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phase 4 trial
(post-marketing surveillance)
— A study carried out after a drug has received a marketing licence, to find out more about its effects, including long term harms and benefits; … (read more)
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PICO
(PICOT)
— Commonly used acronym for the key components of a research question: Patient (or population), Intervention (treatment, test or exposure), Comparison, and Outcome; … (read more)
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placebo
— An inert substance, device or procedure used as a comparator in studies assessing the effects of a treatment; … (read more)
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placebo effect
— Desirable effects that are or could be caused by an “inactive” treatment, presumed to act psychologically through suggestion; … (read more)
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placebo, double dummy see double dummy
(double dummy placebo)
— The use of two different placebos to achieve blinding when the treatments being compared in a study are obviously different; e.g. a tablet and an injection; … (read more)
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planned analysis
— Analyses planned before starting data collection and pre-specified in study protocols; … (read more)
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play of chance
(random error)
— In treatment comparisons, a type of error that may affect the results because too few events or outcomes have been observed to provide a reliable measure of the treatment effects; … (read more)
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positive predictive value
(PPV)
— The proportion of people with a positive test result who have the target condition of interest; … (read more)
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PPI
— Patient and Public Involvement. In health research refers to research carried out ‘with’ or ‘by’ members of the public (especially patients) rather than ‘to’, ‘about’ or ‘for’ them.; … (read more)
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pragmatic trail
(effectiveness trial)
— A study designed to assess the effects of a treatment given in the circumstances of everyday practice; … (read more)
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pre-test probability
(prevalence)
— For screening and diagnostic tests, the likelihood that someone has the target condition for which the test is being used; … (read more)
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precision
— The extent to which errors due to the play of chance on the results of a study are likely to have occurred; … (read more)
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predictive value, negative see negative predictive value
(NPV)
— The proportion of people with a negative test result who do not have the disease or target condition of interest; … (read more)
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prevalence
— The proportion of a population having a particular condition or characteristic; … (read more)
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primary outcome
(main outcome, primary end point,)
— Outcomes measured in treatment comparisons, which have been pre-specified as the most important in looking for potential benefits or harms of the treatments being compared; … (read more)
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prioritisation
— The process of deciding what is most important. In research prioritisation, this means deciding what research questions should be looked at.; … (read more)
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prognosis
— The usual course and outcome of a condition; … (read more)
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prognostic variable
(prognostic marker)
— A characteristic or combination of characteristics known to be associated with the course of a health condition; … (read more)
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protocol or study plan
— The document providing detailed plans for a study; … (read more)