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Glossary of terms used in health research - A

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  • A priori
    • A priori comparisons are planned in advance of any data analysis. They are more reliable than post-hoc comparisons.
  • Abbreviation
    • MeSH - Wikipedia
      A shortened form of a word or phrase.
      Shortened forms of written words or phrases used for brevity.
      Abbreviations [MeSH - publication type]: works consisting of lists of shortened forms of written words or phrases used for brevity. Acronyms are included here.
  • Aborted fetus
    • MeSH
      A mammalian fetus expelled by induced abortion or spontaneous abortion.
  • Abortion rate
    • The number of abortions per 1,000 women ages 15-44 or 15-49 in a given year.
  • Abortion ratio
    • The number of abortions per 1,000 live births in a given year.
  • Absolute difference
    • The absolute difference in rates of good or harmful outcomes between experimental groups (experimental event rate, or EER) and control groups (control event rate, or CER), calculated as the event rate in the experimental group minus the event rate in the control group (EER – CER). For instance, if the rate of adverse events is 20% in the control group and 10% in the treatment group, the absolute difference is 20% – 10% = 10%.
  • Absolute poverty
    • Wikipedia
      The inability to meet basic human needs, such as food, shelter and, avoidance of disease.
      A condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information. It depends not only on income but also on access to services.
  • Absolute risk
    • The probability that an individual will experience the specified outcome during a specified period. It lies in the range 0 to 1, or is expressed as a percentage. In contrast to common usage, the word "risk" may refer to adverse events (such as myocardial infarction) or desirable events (such as cure).
      The risk of an event (e.g., if 10 of 100 patients have an event, the absolute risk is 10% expressed as a percentage, or 0.10 expressed as a proportion).
  • Absolute risk increase
    • Wikipedia
      The absolute arithmetic difference in rates of harmful outcomes between experimental groups (experimental event rate, or EER) and control groups (control event rate, or CER), calculated as rate of harmful outcome in experimental group minus rate of harmful outcome in control group (EER – CER). Typically used to describe a harmful exposure or intervention (e.g., if the rate of adverse outcomes is 20% in treatment and 10% in control, the absolute risk increase would be 10% expressed as a percentage and 0.10 expressed as a proportion).
  • Absolute risk reduction
    • Wikipedia
      Decrease in risk of a given activity or treatment in relation to a control activity or treatment.
      The absolute difference (risk difference) in rates of harmful outcomes between experimental groups (experimental event rate, or EER) and control groups (control event rate, or CER), calculated as the rate of harmful outcome in the control group minus the rate of harmful outcome in the experimental group (CER – EER). Typically used to describe a beneficial exposure or intervention (e.g., if 20% of patients in the control group have an adverse event, as do 10% among treated patients, the ARR or risk difference would be 10% expressed as a percentage or 0.10 expressed as a proportion).
  • Abstract
    • Wikipedia
      A brief summary of a research article, thesis, review, conference proceeding or any in-depth analysis of a particular subject or discipline.
      Abstracts [MeSH - publication type]: works consisting of lists of publications on a subject and that provide full annotated bibliographical information together with substantive summaries or condensations of the facts, ideas, or opinions presented in each publication listed.
  • Academic clinical trials
    • Wikipedia
      Academic clinical trials are run at academic sites, such as medical schools, academic hospitals, and universities; and non-academic sites which may be managed by so-called site management organizations. Site management organizations are for-profit organizations which enlist and manage the physician practice sites that actually recruit and follow patients enrolled in clinical trials.
  • Academic detailing
    • Wikipedia
      Academic detailing is university or non-commercial-based educational outreach.
      A strategy for changing clinician behavior. Use of a trained person who meets with professionals in their practice settings to provide information with the intent of changing their practice. The pharmaceutical industry frequently uses this strategy, to which the term detailing is applied. Academic detailing is such an interaction initiated by an academic group or institution rather than the pharmaceutical industry.
  • Academic dissertation
    • MeSH - Wikipedia
      Dissertations embodying results of original research and especially substantiating a specific view, e.g., substantial papers written by candidates for an academic degree under the individual direction of a professor or papers written by undergraduates desirous of achieving honors or distinction.
      Academic dissertations [MeSH - publication type]; works consisting of formal presentations made usually to fulfill requirements for an academic degree.
  • Acceptability
    • Degree to which a service meets the cultural needs and standards of a community. This in turn will affect utilization of that service.
      A reflection of the willingness of surveillance staff to implement the system, and the end users of the data to accept and use the data generated by the system.
  • Access to health services
    • The perceptions and experiences of people as to their ease in reaching health services or health facilities in terms of location, time, and ease of approach.
  • Accessibility of health services
    • MeSH
      Aspects of the structure of health services or health facilities that enhance the ability of people to reach a health care practitioner, in terms of location, time, and ease of approach.
      The degree to which individuals are inhibited or facilitated in their ability to gain entry to and to receive care and services from the health care system. Factors influencing this ability include geographic, architectural, transportational, and financial considerations, among others.
      Also called health services accessibility.
  • Accident prevention
    • MeSH
      Efforts and designs to reduce the incidence of unexpected undesirable events in various environments and situations.
  • Accountability
    • Wikipedia
      Obligation to demonstrate that work has been conducted in compliance with agreed rules and standards or to report fairly and accurately on performance result vis-a-vis mandated roles and/or plans. Accountability is the means used to hold persons/entities responsible for their actions.
  • Accreditation
    • MeSH - Wikipedia
      The process by which an authorized agency or organization evaluates and recognizes an institution or an individual according to a set of “standards” describing the structures and processes that contribute to desirable patient outcomes.
      Certification as complying with a standard set by non-governmental organizations, applied for by institutions, programs, and facilities on a voluntary basis.
  • Achievable health impact
    • The change in health status that would be expected to follow a specified change in the level of a risk factor, in relation to an intervention.
      Also called avoidable burden of disease.
  • Action research
    • Wikipedia
      A style of research in which the researchers work with the people and for the people, rather than undertake research on them. The focus of action research is on generating solutions to problems identified by the people who are going to use the results of research.
  • Active alternatives
    • The set of diagnoses that can plausibly explain a patient’s presentation.
  • Activities of daily living
    • MeSH - Wikipedia
      The tasks of everyday life. These activities include eating, dressing, getting into or out of a bed or chair, taking a bath or shower, and using the toilet. Instrumental activities of daily living are activities related to independent living and include preparing meals, managing money, shopping, doing housework, and using a telephone. Also called ADL.
      The performance of the basic activities of self care, such as dressing, ambulation, or eating.
  • Actuarial analysis
    • MeSH
      The application of probability and statistical methods to calculate the risk of occurrence of any event, such as onset of illness, recurrent disease, hospitalization, disability, or death. It may include calculation of the anticipated money costs of such events and of the premiums necessary to provide for payment of such costs.
  • Acute care (short-stay)
    • Wikipedia
      Hospitals with an average length of stay of 30 days or less.
  • Additive
    • Describes any trait that increases proportionately in expression when comparing those with no copy, 1 copy, or 2 copies of that allele, i.e., those with 1 copy of the allele show more of the trait than those without, and in turn, those with 2 copies show more of the trait than those with 1 copy.
  • Additive model
    • Wikipedia
      A statistical model in which the combined effect of several factors is the sum of the effects produced by each of the factors in the absence of the others. For example, if one factor increases risk by a% and a second factor by b%, the additive combined effect of the two factors is (a + b)%.
  • Addresses
    • Addresses [MeSH - publication type]: works consisting of speeches, orations, or written statements, usually formal, directed to a particular group of persons. These are different from lectures that are usually delivered to classes for instructional purposes.
  • Adequacy
    • Application of measures, technologies, and resources which are qualitatively and quantitatively sufficient for achieving the desired goal.
  • Adjusted analysis
    • An analysis that controls (adjusts) for baseline imbalances in important patient characteristics.
      Usually refers to attempts to control (adjust) for baseline imbalances in important patient characteristics. Sometimes used to refer to adjustments of P value to take account of multiple testing.
  • Adjusted rate
    • Term used when results have undergone statistical transformation to permit fair comparison between groups differing in some characteristic that may affect risk of disease.
  • Adjustment
    • A summarizing procedure in which the effects of differences in composition of the populations being compared have been minimized by statistical methods.
  • Adolescent
    • MeSH
      A person 13 to 18 years of age.
  • Adolescent fertility rate
    • The annual number of births to women aged 15-19 years per 1,000 women in that age group. It is also referred to as the age-specific fertility rate for women aged 15-19.
  • Adolescent health services
    • MeSH
      Organized services to provide health care to adolescents, ages ranging from 13 through 18 years.
  • Adolescent medicine
    • MeSH - Wikipedia
      A medical subspecialty that focuses on care of patients who are in the adolescent period of development.
      A branch of medicine pertaining to the diagnosis and treatment of diseases occurring during the period beginning with puberty until the cessation of somatic growth.
  • Adult literacy rate
    • The percentage of population aged 15 years and over who can both read and write with understanding a short simple statement on his/her everyday life. Generally, ‘literacy’ also encompasses ‘numeracy’, the ability to make simple arithmetic calculations.
  • Adult mortality rate
    • Probability that a 15 year old person will die before reaching his/her 60th birthday. The probability of dying between the ages of 15 and 60 years (per 1,000 population) per year among a hypothetical cohort of 100,000 people that would experience the age-specific mortality rate of the reporting year.
  • Adverse drug reaction
    • Wikipedia
      An unwanted effect caused by the administration of drugs. Onset may be sudden or develop over time.
      In the preapproval clinical experience with a new medicinal product or its new usages, particularly as the therapeutic dose(s) may not be established, all noxious and unintended responses to a medicinal product related to any dose should be considered adverse drug reactions. The phrase "responses to a medicinal product" means that a causal relationship between a medicinal product and an adverse event is at least a reasonable possibility, i.e., the relationship cannot be ruled out. Regarding marketed medicinal products: A response to a drug that is noxious and unintended and that occurs at doses normally used in man for prophylaxis, diagnosis, or therapy of diseases or for modification of physiological function.
      Also called adverse reaction.
  • Adverse drug reaction reporting systems
    • MeSH
      Systems developed for collecting reports from government agencies, manufacturers, hospitals, physicians, and other sources on adverse drug reactions.
  • Adverse effect
    • Wikipedia
      An unwanted side effect of treatment.
      A harmful and undesired effect resulting from a medication or other intervention such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect, and may result from an unsuitable or incorrect dosage or procedure, which could be due to medical error.
      An adverse event for which the causal relation between the drug/intervention and the event is at least a reasonable possibility. The term ‘adverse effect’ applies to all interventions, while ‘adverse drug reaction’ (ADR) is used only with drugs. In the case of drugs an adverse effect tends to be seen from the point of view of the drug and an adverse reaction is seen from the point of view of the patient.
  • Adverse event
    • Wikipedia
      An unexpected medical problem that happens during treatment with a drug or other therapy. Adverse events do not have to be caused by the drug or therapy, and they may be mild, moderate, or severe.
      An adverse outcome that occurs during or after the use of a drug or other intervention but is not necessarily caused by it.
  • Advice
    • Advice is a statement or opinion as to how one should proceed. The purpose of advice is to influence. Advice can be based on research evidence, professional experience, personal opinion/experiences or even societal norms.
  • Advocacy
    • Wikipedia
      A conceptual and strategic framework that spells out goals and objectives, priority themes and key strategies to be addressed by relevant operatives at all levels. It defines, for example, an agreed vision within the context of humanitarian coordination and traces a road map of actions to be undertaken to realize this vision.
      Literally, “coming to the aid of others.” Refers to the process of supporting legal, policy, or scientific positions, decisions, and arguments.
  • Advocacy and support groups
    • Wikipedia
      Organizations and groups that actively support participants and their families with valuable resources, including self-empowerment and survival tools.
  • Affordability
    • Extent to which the intended clients of a service can pay for it.
  • Age-dependency ratio
    • The ratio of persons in the ages defined as dependent (under 15 years and over 64 years) to persons in the ages defined as economically productive (15-64 years) in a population.
  • Age distribution
    • MeSH
      The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.
  • Age factors
    • MeSH
      Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from aging, a physiological process, and time factors which refers only to the passage of time.
  • Age of consent
    • Wikipedia
      While the phrase age of consent typically does not appear in legal statutes, when used in relation to sexual activity, the age of consent is the minimum age at which a person is considered to be legally competent of consenting to sexual acts. The European Union calls it the legal age for sexual activities.
  • Age-sex structure
    • Wikipedia
      The composition of a population as determined by the number or proportion of males and females in each age category. The age-sex structure of a population is the cumulative result of past trends in fertility, mortality, and migration. Information on age-sex composition is essential for the description and analysis of many other types of demographic data.
  • Age-specific mortality rate
    • Mortality rate in a specific age group.
      A mortality rate limited to a particular age group. The numerator is the number of deaths in that age group; the denominator is the number of persons in that age group in the population.
  • Age specific rate
    • Age-specific rates are calculated by dividing the number of cases occurring in each specified age group by the corresponding population sampled in the same age group. Sometimes, this is expressed as a rate per 100,000 population; other times as a percent of sampled population. This rate may be calculated for a particular age and sex grouping to show how a risk factor, occurrence of death or incidence of a disease changes with age and sex. Example: Age specific current daily smoker rate for males aged 70-74 years (%) = number of male current daily smokers aged 70-74 years/ total population of males aged 70-74 years sampled x 100.
      Rate obtained for specific age groups (for example, age-specific fertility rate, death rate, marriage rate, illiteracy rate, or school enrollment rate).
  • Age standardization
    • Wikipedia
      Rates are adjusted for age to facilitate comparisons between populations which have different age structures. (There are two different methods commonly used to adjust for age, direct and indirect. We use direct standardization in which age-specific rates are multiplied against a constant population, the WHO standard population EIP 1999).
      In epidemiology and demography, age adjustment, also called age standardization, is a technique used to better allow populations to be compared when the age profiles of the populations are quite different.
  • Age-standardized mortality rate
    • Wikipedia
      The age-standardized mortality rate is a weighted average of the age-specific mortality rates per 100,000 persons, where the weights are the proportions of persons in the corresponding age groups of the WHO standard population.
      Age-standardized mortality rates are used to compare the mortality rates of places without being skewed by the difference in age distributions from place to place.
      Mortality rate that takes into account the age structure of the population to which it refers. Used to compare mortality in populations with very different age structures.
      A mortality rate statistically modified to eliminate the effect of different age distributions in the different populations.
      Also called age-adjusted mortality rate.
  • Agent
    • A factor, such as a microorganism, chemical substance, or form of radiation, whose presence, excessive presence, or (in deficiency diseases) relative absence is essential for the occurrence of a disease.
  • Aging
    • MeSH - Wikipedia
      The accumulation of changes in an organism or object over time. Aging in humans refers to a multidimensional process of physical, psychological, and social change.
      The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
  • Aging of population
    • A process in which the proportions of adults and elderly increase in a population, while the proportions of children and adolescents decrease. This process results in a rise in the median age of the population. Aging occurs when fertility rates decline while life expectancy remains constant or improves at the older ages.
  • Aggregate data
    • Data summarized by groups, for example summary outcome data for treatment and control groups in a controlled trial.
  • Alert threshold
    • The critical number of cases (or indicator, proportion, rate, etc.) that is used to sound an early warning, launch an investigation at the start of an epidemic and prepare to respond to the epidemic.
  • Alerting systems
    • A strategy for changing clinician behavior. A type of computer decision support system that alerts the clinician to a circumstance that might require clinical action (e.g., a system that highlights out-of-range laboratory values).
  • Algorithm
    • MeSH - Wikipedia
      An explicit description of an ordered sequence of steps with branching logic that can be applied under specific clinical circumstances. The logic of an algorithm is as follows: if a, then do x; if b, then do y; etc.
      A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.
  • Allocation concealment
    • Wikipedia
      The procedure for protecting the randomization process so that the treatment to be allocated is not known before the patient is entered into the study.
      A technique used to prevent selection bias by concealing the allocation sequence from those assigning participants to intervention groups, until the moment of assignment. Allocation concealment prevents researchers from (unconsciously or otherwise) influencing which participants are assigned to a given intervention group.
      The process used to ensure that the person deciding to enter a participant into a randomized controlled trial does not know the comparison group into which that individual will be allocated. This is distinct from blinding, and is aimed at preventing selection bias. Some attempts at concealing allocation are more prone to manipulation than others, and the method of allocation concealment is used as an assessment of the quality of a trial.
  • Allocation ratio
    • The ratio of intended numbers of participants in each of the comparison groups. For two group trials, the allocation ratio is usually 1:1, but unequal allocation (such as 1:2) is sometimes used.
  • Allocation sequence
    • A list of intervention groups, randomly ordered, used to assign sequentially enrolled participants to intervention groups. Also termed the "assignment schedule", "randomization schedule", or "randomization list".
  • Allocative efficiency
    • Wikipedia
      With allocative efficiency, all objectives compete with each other for implementation. For example, “should we allocate more resources to the prevention of childhood injury or improve clinics for children with chronic disease such as asthma?” is a question of allocative efficiency. Allocative efficiency is about whether to do something, or how much of it to do, rather than how to do it. Allocative efficiency in health care is achieved when it is not possible to increase the overall benefits produced by the health system by reallocating resources between programs. This occurs where the ratio of marginal benefits to marginal costs is equal across all health care programs in the system.
  • Alpha level
    • The probability of erroneously concluding there is a difference between comparison groups when there is in fact no difference (type I error). Typically, investigators decide on the chance of a false-positive result they are willing to accept when they plan the sample size for a study (e.g., investigators often set alpha level at 0.05).
  • Alternative hypothesis
    • Wikipedia
      The hypothesis that the researcher is testing in the study. In scientific methodology, we start with the assumption that it is not true until proved otherwise, by rejecting the null hypothesis.
      The hypothesis, to be adopted if the null hypothesis proves implausible, in which exposure is associated with disease.
  • Ambulatory care
    • MeSH - Wikipedia
      All types of health services provided to patients who are not confined to an institutional bed as inpatients during the time services are rendered.
      Health care services provided to patients on an ambulatory basis, rather than by admission to a hospital or other health care facility. The services may be a part of a hospital, augmenting its inpatient services, or may be provided at a free-standing facility.
  • Ambulatory care facilities
    • MeSH
      Those facilities which administer health services to individuals who do not require hospitalization or institutionalization.
  • Analysis of variance
    • MeSH
      A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.
  • Analytic epidemiology
    • The aspect of epidemiology concerned with the search for health-related causes and effects. Uses comparison groups, which provide baseline data, to quantify the association between exposures and outcomes, and test hypotheses about causal relationships.
  • Analytical study
    • An observational study that describes associations and analyses them for possible cause and effect.
      A comparative study intended to identify and quantify associations, test hypotheses, and identify causes. Two common types are cohort study and case-control study.
  • Anecdote
    • MeSH - Wikipedia
      A short, free-standing tale narrating an interesting or amusing biographical incident.
      Anecdotes [MeSH - publication type]: works consisting of brief accounts or narratives of incidents or events.
  • Animal care committees
    • MeSH
      Institutional committees established to protect the welfare of animals used in research and education. The 1971 NIH Guide for the Care and Use of Laboratory Animals introduced the policy that institutions using warm-blooded animals in projects supported by NIH grants either be accredited by a recognized professional laboratory animal accrediting body or establish its own committee to evaluate animal care; the Public Health Service adopted a policy in 1979 requiring such committees; and the 1985 amendments to the Animal Welfare Act mandate review and approval of federally funded research with animals by a formally designated Institutional Animal Care and Use Committee (IACUC).
  • Animal experimentation
    • MeSH - Wikipedia
      Animal testing, also known as animal experimentation, animal research, and in vivo testing, is the use of non-human animals in experiments, particularly model organisms such as nematode worms, fruit flies, zebrafish, and mice.
      The use of animals as investigational subjects.
  • Animal model
    • MeSH - Wikipedia
      An animal with a disease either the same as or like a disease in humans. Animal models are used to study the development and progression of diseases and to test new treatments before they are given to humans.
      Non-human animals, selected because of specific characteristics, for use in experimental research, teaching, or testing.
  • Animal study
    • Wikipedia
      A laboratory experiment using animals to study the development and progression of diseases. Animal studies also test how safe and effective new treatments are before they are tested in people.
  • Annual birth average
    • Total number of live births expected in a specific year, for a given country, territory, or geographic area.
  • Annual death average
    • Total number of deaths expected in a specific year, for a given country, territory, or geographic area.
  • Annual population growth rate
    • Average exponential rate of annual growth of the population over a given period.
      The annual average rate of change of population size, for a given country, territory, or geographic area, during a specified period. It expresses the ratio between the annual increase in the population size and the total population for that year, usually multiplied by 100. The annual increase in the population size is defined as a sum of differences: the difference between births less deaths and the difference between immigrants less emigrants, in a given country, territory or geographic area at a given year.
  • Annual report
    • MeSH - Wikipedia
      Annual statements reviewing the status of the administrative and operational functions and accomplishments of an institution or organization.
      Annual reports [MeSH - publication type]: works consisting of annual statements concerning the administrative and operational functions of an institution or organization.
  • Anonymous linked information
    • Information which cannot be linked to the person to whom it refers, ensuring that the investigator cannot know the identity of the person and there is complete confidentiality in a study.
  • Anonymous testing
    • MeSH
      Testing in which the source of the specimen or the person being tested is not individually identified.
  • Antenatal care
    • MeSH
      Antenatal care constitutes screening for health and socioeconomic conditions likely to increase the possibility of specific adverse pregnancy outcomes, providing therapeutic interventions known to be effective; and educating pregnant women about planning for safe birth, emergencies during pregnancy and how to deal with them.
      Care provided the pregnant woman in order to prevent complications, and decrease the incidence of maternal and prenatal mortality.
      Also called prenatal care.
  • Antenatal care coverage
    • Percentage of women who used antenatal care provided by skilled health personnel for reasons related to pregnancy at least once during pregnancy, as a percentage of live births in a given time period.
  • Antenatal care coverage - at least four visits
    • The percentage of women aged 15-49 with a live birth in a given time period that received antenatal care four or more times. Due to data limitations, it is not possible to determine the type of provider for each visit. Numerator: The number of women aged 15-49 with a live birth in a given time period that received antenatal care four or more times. Denominator: Total number of women aged 15-49 with a live birth in the same period.
  • Antenatal care coverage - at least one visit
    • The percentage of women aged 15-49 with a live birth in a given time period that received antenatal care provided by skilled health personnel (doctors, nurses, or midwives) at least once during pregnancy. Numerator: The number of women aged 15-49 with a live birth in a given time period that received antenatal care provided by skilled health personnel (doctors, nurses or midwives) at least once during pregnancy Denominator: Total number of women aged 15-49 with a live birth in the same period.
  • Anthropometry
    • MeSH - Wikipedia
      Refers to the measurement of the human individual for the purposes of understanding human physical variation.
      The technique that deals with the measurement of the size, weight, and proportions of the human or other primate body.
  • APACHE
    • MeSH
      An acronym for Acute Physiology and Chronic Health Evaluation, a scoring system using routinely collected data and providing an accurate, objective description for a broad range of intensive care unit admissions, measuring severity of illness in critically ill patients.
  • Applicability
    • The application of the results from clinical trials to individual people. A randomized trial only provides direct evidence of causality within that specific trial. It takes an additional logical step to apply this result to a specific individual. Individual characteristics will affect the outcome for this person.
      The degree to which the results of an observation, study or review hold true in other settings.
  • Applicable regulatory requirement
    • Wikipedia
      Any law(s) and regulation(s) addressing the conduct of clinical trials of investigational products of the jurisdiction where trial is conducted.
  • Applied epidemiology
    • The application or practice of epidemiology to address public health issues.
  • Appropriate(ness)
    • If an expected health benefit exceeds the expected negative consequences by a large enough margin to justify performing the procedure rather than other alternatives.
  • Approval
    • In relation to institutional review boards (IRBs): the affirmative decision of the IRB that the clinical trial has been reviewed and may be conducted at the institution site within the constraints set forth by the IRB, the institution, good clinical practice (GCP), and the applicable regulatory requirements.
  • Approved drugs
    • Wikipedia
      In the U.S., the Food and Drug Administration (FDA) must approve a substance as a drug before it can be marketed. The approval process involves several steps including pre-clinical laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the manufacturer of the drug, FDA review of the application, and FDA approval/rejection of application.
  • Area under curve
    • MeSH
      A statistical means of summarizing information from a series of measurements on one individual. It is frequently used in clinical pharmacology where the AUC from serum levels can be interpreted as the total uptake of whatever has been administered. As a plot of the concentration of a drug against time, after a single dose of medicine, producing a standard shape curve, it is a means of comparing the bioavailability of the same drug made by different companies.
  • Argument
    • Wikipedia
      Argument refers to a sequence of statements in which the premise purports to give reason to accept the conclusion.
  • Arithmetic mean
    • Wikipedia
      In mathematics and statistics, the arithmetic mean (or simply the mean) of a list of numbers is the sum of all of the list divided by the number of items in the list. If the list is a statistical population, then the mean of that population is called a population mean. If the list is a statistical sample, we call the resulting statistic a sample mean.
      The measure of central location commonly called the average. It is calculated by adding together all the individual values in a group of measurements and dividing by the number of values in the group.
  • Arm
    • In a controlled trial refers to a group of participants allocated a particular treatment. In a randomized controlled trial, allocation to different arms is determined by the randomization procedure. Many controlled trials have two arms, a group of participants assigned to an experimental intervention (sometimes called the treatment arm) and a group of participants assigned to a control (the control arm). Trials may have more than two arms, with more than one experimental arm and/or more than one control arm.
  • Ascertainment bias
    • Wikipedia
      Systematic distortion of the results of a randomized trial as a result of knowledge of the group assignment by the person assessing outcome, whether an investigator or the participant themselves.
  • Assessment
    • A systematic or non-systematic way of gathering relevant information, analyzing and making judgment on the basis of the available information.
  • Assignment
    • The process in an experiment where the researcher allocates subjects to two or more groups, trying to achieve having groups as identical as possible to allow a valid comparison of the results. Matching and random assignment are the two most common methods.
  • Assisted reproductive technology
    • MeSH - Wikipedia
      All treatments or procedures that include the in vitro handling of both human oocytes and sperm, or embryos, for the purpose of establishing a pregnancy. This includes, but is not limited to, in vitro fertilization and embryo transfer, gamete intrafallopian transfer, zygote intrafallopian transfer, tubal embryo transfer, gamete and embryo cryopreservation, oocyte and embryo donation, and gestational surrogacy. Assisted reproductive technology (ART) does not include assisted insemination (artificial insemination) using sperm from either a woman's partner or a sperm donor.
      Clinical and laboratory techniques used to enhance fertility in humans and animals.
      Also called assisted reproductive technics.
  • Association
    • A relationship between two characteristics, such that as one changes, the other changes in a predictable way. For example, statistics demonstrate that there is an association between smoking and lung cancer. In a positive association, one quantity increases as the other one increases (as with smoking and lung cancer). In a negative association, an increase in one quantity corresponds to a decrease in the other. Association does not necessarily imply a causal effect. (Also called correlation.)
      Statistical relationship between two or more events, characteristics, or other variables.
  • Atlas
    • MeSH - Wikipedia
      A collection of maps.
      Atlases [MeSH - publication type]: works consisting of collections of illustrative plates, charts, etc., usually with explanatory captions.
  • Attack rate
    • Wikipedia
      In epidemiology, an attack rate is the cumulative incidence of infection in a group of people observed over a period of time during an epidemic, usually in relation to foodborne illness. The term is defined as the number of exposed persons infected with the disease divided by the total number of exposed persons. It is measured from the beginning of an outbreak to the end of the outbreak.
      A variant of an incident rate, applied to a narrowly defined population observed for a limited period of time, such as during an epidemic.
  • Attributable health impact
    • The amount of ill health that can be attributed to a particular risk factor.
  • Attributable proportion
    • A measure of the public health impact of a causative factor; proportion of a disease in a group that is exposed to a particular factor which can be attributed to their exposure to that factor.
  • Attributable risk
    • Wikipedia
      An estimate to quantify the contribution which a particular risk factor makes in producing the disease within a population.
  • Attrition
    • Wikipedia
      The loss of participants during the course of a study. (Also called loss to follow up.) Participants that are lost during the study are often call dropouts.
  • Attrition bias
    • Wikipedia
      Systematic differences between comparison groups in withdrawals or exclusions of participants from the results of a study. For example, participants may drop out of a study because of side effects of an intervention, and excluding these participants from the analysis could result in an overestimate of the effectiveness of the intervention, especially when the proportion dropping out varies by treatment group.
  • Audit
    • Wikipedia
      A systematic and independent examination of trial-related activities and documents to determine whether the evaluated trial-related activities were conducted, and the data were recorded, analyzed, and accurately reported according to the protocol, sponsor's standard operating procedures (SOPs), good clinical practice (GCP), and the applicable regulatory requirement(s).
  • Audit certificate
    • A declaration of confirmation by the auditor that an audit has taken place.
  • Audit report
    • Wikipedia
      A written evaluation by the sponsor's auditor of the results of the audit.
  • Audit trail
    • Wikipedia
      Documentation that allows reconstruction of the course of events.
  • Autocorrelation
    • Wikipedia
      Occurs when the likelihood of an observation is not independent of its relationship with other observations. For example, autocorrelation occurs when a good day for a patient with chronic disease is more likely to follow a "good day" than a "bad day."
  • Autonomy
    • Wikipedia
      Literally, self ruling. Related to, and sometimes used in lieu of the bioethical principle of respect for persons. Implies intentionality and freedom from coercion. In the Kantian tradition, autonomy implies freely embracing a moral obligation. In public health, individual autonomy may be limited by interventions applied to populations.
  • Availability
    • Identifies the presence or absence of needed health care services.
  • Average
    • Wikipedia
      A measure for the central tendency of a sample of observations. The term average is most often used for the arithmetic mean, but sometimes also for the median. For instance, suppose the yearly income of five people is $50,000, $80,000, $100,000, $120,000, and $650,000. The arithmetic mean is the sum of these values divided by their number, that is, $200,000. The median is obtained by ranking the values (as above) and taking the one in the middle, that is, $100,000. When the distribution is asymmetric, as it is often with income, the mean and the median are not the same, and it can be the case that most people earn less than the mean.
  • Average cost
    • Wikipedia
      The cost per unit of output. Each of the three cost concepts discussed above can be expressed as an average cost: average fixed costs, average variable costs and average total costs, by dividing cost by the measure of output (patient days, hospital admissions, diagnostic tests performed, etc).
  • Average length of stay
    • Wikipedia
      Average length of stay is computed by dividing the (total) number of days in inpatient or acute care institutions by the number of discharges (or admissions).