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Glossary of terms used in health research - B

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  • Balancing equation
    • A basic demographic formula used to estimate total population change between two points in time — or to estimate any unknown component of population change, provided that the other components are known. The balancing equation includes all components of population change: births, deaths, immigration, emigration, in-migration, and out-migration.
  • Bar chart
    • Wikipedia
      A graphic method of describing the data, where the frequency of a particular category is reflected in the height of the bar in the graph.
      A visual display of the size of the different categories of a variable. Each category or value of the variable is represented by a bar.
  • Baseline
    • Wikipedia
      Information gathered at the beginning of a study from which variations found in the study are measured.
      A known value or quantity with which an unknown is compared when measured or assessed.
      The initial time point in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested. At this reference point, measurable values such as CD4 count are recorded. Safety and efficacy of a drug are often determined by monitoring changes from the baseline values.
      An initial measurement that is taken at an early time point to represent a beginning condition, and is used for comparison over time to look for changes. For example, the size of a tumor will be measured before treatment (baseline) and then afterwards to see if the treatment had an effect.
      A phase in an intervention study where the participants have not received any intervention.
      An observation or value that represents the background level of a measurable quantity.
  • Baseline assessment
    • Is an assessment performed during the design phase of a surveillance plan of action. It provides information on the existing situation, forms the basis for the development of the plan of action, and provides baseline data against which prospective changes in the surveillance system are progressively assessed or measured.
  • Baseline characteristics
    • Values of demographic, clinical and other variables collected for each participant at the beginning of a trial, before the intervention is administered.
  • Baseline data
    • Data or measurements collected at the outset of implementation of a surveillance system or of strengthening activities, or a set of indicators that have been identified to monitor and evaluate the performance of a surveillance and response system. For example, the baseline mortality rate (or non-crisis mortality rate) is mortality rate before the crisis.
  • Baseline risk
    • The proportion or percentage of study participants in the control group in whom an adverse outcome is observed.
  • Basic reproduction number
    • MeSH - Wikipedia
      In epidemiology, the basic reproduction number (sometimes called basic reproductive rate or basic reproductive ratio) of an infection is the mean number of secondary cases a typical single infected case will cause in a population with no immunity to the disease in the absence of interventions to control the infection.
      The expected number of new cases of an infection caused by an infected individual, in a population consisting of susceptible contacts only.
  • Basic risk
    • An expression of the likelihood that a particular event will occur within a particular population.
  • Bayes theorem
    • MeSH - Wikipedia
      A probability theorem used to update the probability of an event in the light of a piece of new evidence. A common application is in diagnosis, where the prior probability of disease, obtained from population data, is updated to a posterior probability in the light of a positive or negative result from a diagnostic test.
      A theorem in probability theory named for Thomas Bayes (1702-1761). In epidemiology, it is used to obtain the probability of disease in a group of people with some characteristic on the basis of the overall rate of that disease and of the likelihoods of that characteristic in healthy and diseased individuals. The most familiar application is in clinical decision analysis where it is used for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result.
  • Bayesian approaches
    • Wikipedia
      Approaches to data analysis that provide a posterior probability distribution for some parameter (e.g. treatment effect), derived from the observed data and a prior probability distribution for the parameter. The posterior distribution is then used as the basis for statistical inference.
  • Bayesian statistics
    • Wikipedia
      An approach to statistics based on application of Bayes’ theorem that can be used in single studies or meta-analysis. A Bayesian analysis uses Bayes' theorem to transform a prior distribution for an unknown quantity (e.g. an odds ratio) into a posterior distribution for the same quantity, in light of the results of a study or studies. The prior distribution may be based on external evidence, common sense or subjective opinion. Statistical inferences are made by extracting information from the posterior distribution, and may be presented as point estimates, and credible intervals (the Bayesian equivalent of confidence intervals).
  • Bed conversion
    • MeSH
      The reallocation of beds from one type of care service to another, as in converting acute care beds to long term care beds.
  • Bed days
    • A day during which a person is confined to a bed and in which the patient stays overnight in a hospital.
  • Bed occupancy
    • MeSH
      A measure of inpatient health facility use based upon the average number or proportion of beds occupied for a given period of time.
  • Before-and-after study
    • A method of control in which results from experimental subjects are compared with outcomes from patients treated before the new intervention was available. These are called historic controls.
  • Behavioral research
    • MeSH
      Research that involves the application of the behavioral and social sciences to the study of the actions or reactions of persons or animals in response to external or internal stimuli.
  • Bell-shaped curve
    • Wikipedia
      The characteristic shape of the curve of a normal distribution, where the data are equally distributed around the mean.
  • Benchmark
    • Reference point or standard against which performance or achievements can be assessed. A benchmark refers to the performance that has been achieved in the recent past by other comparable organizations, or what can be reasonably inferred to have been achieved in the circumstances.
  • Benchmarking
    • MeSH - Wikipedia
      A process of measuring another organization’s product or service according to specified standards in order to compare it with and improve one’s own product or service.
      Method of measuring performance against established standards of best practice.
  • Beneficence
    • MeSH - Wikipedia
      An ethical principle implying that every effort should be made to maximize the benefits to the subjects in health research.
      Literally, doing good; in bioethics, a prima facie principle underlying utilitarian approaches. Implies an obligation to promote benefits of things judged to be good, typically balancing produced goods against risks or harms. In public health, beneficence implies acting in the best interest of the population or society as a whole.
      The state or quality of being kind, charitable, or beneficial.
  • Benefits
    • Benefits are potential favorable effects on health or its determinants, whether or not intended by a proposal.
  • Best evidence
    • Systematic reviews of RCTs are the best method for revealing the effects of a therapeutic intervention.
  • Best practice
    • Wikipedia
      In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with the best practice. Also called standard therapy or standard of care.
      Best practice(s) refer(s) to interventions that are supposed to lead to desired outcomes.
  • Bias
    • MeSH - Wikipedia
      In a scientific research study or clinical trial, a flaw in the study design or the method of collecting or interpreting information. Biases can lead to incorrect conclusions about what the study or clinical trial showed.
      When a point of view prevents impartial judgment on issues relating to the subject of that point of view. In clinical studies, bias is controlled by blinding and randomization
      The systematic tendency of any factors associated with the design, conduct, analysis and evaluation of the results of a clinical trial to make the estimate of a treatment effect deviate from its true value. Bias introduced through deviations in conduct is referred to as 'operational' bias. The other sources of bias listed above are referred to as 'statistical'.
      In statistics: a systematic error or deviation in results or inferences from the truth. In studies of the effects of health care, the main types of bias arise from systematic differences in the groups that are compared (selection bias), the care that is provided, exposure to other factors apart from the intervention of interest (performance bias), withdrawals or exclusions of people entered into a study (attrition bias) or how outcomes are assessed (detection bias). Reviews of studies may also be particularly affected by reporting bias, where a biased subset of all the relevant data is available.
      Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions.
  • Bias prevention
    • Aspects of the design or conduct of a study designed to prevent bias. For controlled trials, such aspects include randomization, blinding and concealment of allocation.
  • Bibliographic database
    • MeSH - Wikipedia
      A database of bibliographic records.
      Extensive collections, reputedly complete, of references and citations to books, articles, publications, etc., generally on a single subject or specialized subject area. Databases can operate through automated files, libraries, or computer disks. The concept should be differentiated from databases, factual which is used for collections of data and facts apart from bibliographic references to them.
  • Bibliography
    • MeSH - Wikipedia
      A list of books, articles, documents, publications, and other items, usually on a single subject or related subjects.
      Discussion of lists of works, documents or other publications, usually with some relationship between them, e.g., by a given author, on a given subject, or published in a given place, and differing from a catalog in that its contents are restricted to holdings of a single collection, library, or group of libraries.
      Bibliography [MeSH - publication type]: a work consisting of a list of books, articles, documents, publications, and other items, usually on a single subject or related subjects.
  • Binomial distribution
    • MeSH - Wikipedia
      A statistical distribution with known properties describing the number of occurrences of an event in a series of observations. Thus, the number of deaths in the control arm of a controlled trial follows a binomial distribution. The distribution forms the basis for analyses of dichotomous data.
      The probability distribution associated with two mutually exclusive outcomes; used to model cumulative incidence rates and prevalence rates. The Bernoulli distribution is a special case of binomial distribution.
  • Bioavailable
    • Wikipedia
      The ability of a drug or other substance to be absorbed and used by the body. Orally bioavailable means that a drug or other substance that is taken by mouth can be absorbed and used by the body.
  • Biobibliography
    • MeSH
      A biography which includes a list of the writings of the subject person.
      Biobibliography [MeSH - publication type]: works consisting of biographical information as well as lists of the writings of those persons.
  • Biochemical pregnancy
    • A pregnancy diagnosed only by the detection of HCG in serum or urine and that does not develop into a clinical pregnancy.
      Also called preclinical spontaneous abortion/miscarriage.
  • Bioethical issues
    • MeSH
      Clusters of topics that fall within the domain of bioethics, the field of study concerned with value questions that arise in biomedicine and health care delivery.
  • Bioethics
    • MeSH - Wikipedia
      Bioethics is the philosophical study of the ethical controversies brought about by advances in biology and medicine. Bioethicists are concerned with the ethical questions that arise in the relationships among life sciences, biotechnology, medicine, politics, law, philosophy, and theology.
      A field of inquiry and academic discipline at the intersection of ethics and the life sciences. Emerging with an emphasis upon problems faced in the practice of medicine and biomedical research, bioethics has overlapping areas of scholarship and application: theory and method, clinical practice, regulatory policy, research practice, cultural and social concerns,8 and recently, public health and epidemiology.
      A branch of applied ethics that studies the value implications of practices and developments in life sciences, medicine, and health care.
  • Biography
    • MeSH - Wikipedia
      A written account of a person's life and the branch of literature concerned with the lives of people.
      Biography [MeSH - publication type]: works consisting of an account of the events, works, and achievements, personal and professional, during a person's life. It includes articles on the activities and accomplishments of living persons as well as the presentation of an obituary.
  • Bioinformatics
    • MeSH - Wikipedia
      The science of using computers, databases, and math to organize and analyze large amounts of biological, medical, and health information. Information may come from many sources, including patient statistics, tissue specimens, genetics research, and clinical trials.
      A field of biology concerned with the development of techniques for the collection and manipulation of biological data, and the use of such data to make biological discoveries or predictions. This field encompasses all computational methods and theories applicable to molecular biology and areas of computer-based techniques for solving biological problems including manipulation of models and datasets.
      Also called computational biology.
  • Biologic transmission
    • The indirect vector-borne transmission of an infectious agent in which the agent undergoes biologic changes within the vector before being transmitted to a new host.
  • Biological availability
    • MeSH
      The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.
  • Biological drug
    • Wikipedia
      A substance that is made from a living organism or its products and is used in the prevention, diagnosis, or treatment diseases. Biological drugs include antibodies, interleukins, and vaccines. Also called biologic agent or biological agent.
  • Biological marker
    • MeSH - Wikipedia
      A biomarker, or biological marker, is in general a substance used as an indicator of a biological state. It is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.
      Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.
  • Biological plausibility
    • Biological plausibility means that the relation makes sense according to the prevailing understanding of pathobiological processes.
  • Biomedical research
    • MeSH - Wikipedia
      Biomedical research (or experimental medicine), in general simply known as medical research, is the basic research, applied research, or translational research conducted to aid and support the body of knowledge in the field of medicine.
      Research that involves the application of the natural sciences, especially biology and physiology, to medicine.
  • Biometric identification
    • MeSH
      A method of differentiating individuals based on the analysis of qualitative or quantitative biological traits or patterns. This process which has applications in forensics and identity theft prevention includes DNA profiles or DNA fingerprints, hand fingerprints, automated facial recognition, iris scan, hand geometry, retinal scan, vascular patterns, automated voice pattern recognition, and ultrasound of fingers.
  • Biometrics
    • Wikipedia
      The science of collecting and analyzing biologic or health data using statistical methods. Biometrics may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometry.
  • Biometry
    • MeSH - Wikipedia
      The science of collecting and analyzing biologic or health data using statistical methods. Biometry may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometrics.
      The use of statistical and mathematical methods to analyze biological observations and phenomena.
  • Biostatistics
    • MeSH - Wikipedia
      The science of collecting and analyzing biologic or health data using statistical methods. Biostatistics may be used to help learn the possible causes of a disease in a certain group of people. Also called biometry and biometrics.
      The application of statistics to biological systems and organisms involving the retrieval or collection, analysis, reduction, and interpretation of qualitative and quantitative data.
  • Biotechnology
    • MeSH - Wikipedia
      Any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use.
      Body of knowledge related to the use of organisms, cells or cell-derived constituents for the purpose of developing products which are technically, scientifically and clinically useful. Alteration of biologic function at the molecular level (i.e., genetic engineering) is a central focus; laboratory methods used include transfection and cloning technologies, sequence and structure analysis algorithms, computer databases, and gene and protein structure function analysis and prediction.
  • Birth control
    • Wikipedia
      A regimen of one or more actions, devices, sexual practices, or medications followed in order to deliberately prevent or reduce the likelihood of pregnancy or childbirth.
      Practices employed by couples that permit sexual intercourse with reduced likelihood of conception and birth. The term birth control is often used synonymously with such terms as contraception, fertility control, and family planning. But birth control includes abortion to prevent a birth, whereas family planning methods explicitly do not include abortion.
  • Birth interval
    • MeSH
      Elapsed time between a mother’s deliveries. This is sometimes calculated as the time from delivery to the last menstrual period (LMP) of the subsequent pregnancy (called “inter-pregnancy interval”) to avoid confounding by length of the subsequent pregnancy.
      The lengths of intervals between births to women in the population.
  • Birth rate
    • MeSH
      The number of births in a given population per year or other unit of time.
  • Birth rate for unmarried women
    • The number of live births per 1,000 unmarried women (never married, widowed, or divorced) ages 15-49 in a given year.
  • Birth weight
    • MeSH
      Birth weight is the first weight of the fetus or newborn obtained after birth. For live births, birth weight should ideally be measured within the first hour of life before significant postnatal weight loss occurs.
      Weight of the baby (live born or stillborn) at delivery.
      The mass or quantity of heaviness of an individual at BIRTH. It is expressed by units of pounds or kilograms.
  • Births attended by skilled health personnel
    • Percentage of live births attended by skilled health personnel in a given period of time.
  • Births by caesarean section
    • Percentage of births by caesarean section among all live births in a given time period.
  • Blind
    • Wikipedia
      A randomized trial is "Blind" if the participant is not told which arm of the trial he is on. A clinical trial is "Blind" if participants are unaware on whether they are in the experimental or control arm of the study; also called masked.
      A procedure in which one or more parties to the trial are kept unaware of the treatment assignment(s). Single blinding usually refers to the subject(s) being unaware, and double blinding usually refers to the subject(s), investigator(s), monitor, and, in some cases, data analyst(s) being unaware of the treatment assignment(s).
  • Blind assessment
    • The evaluation of an outcome is made without the evaluator  knowing which results are from the test under study and which are from the control or “gold standard”.
  • Blind review
    • The checking and assessment of data during the period of time between trial completion (the last observation on the last subject) and the breaking of the blind, for the purpose of finalizing the planned analysis.
      Medical journals: one common review process is the same as the peer review, except all references to the authors are removed from the article before review by the researchers. This has been particularly important in medical research as there is a strong bias against articles produced by non-physicians, which are more likely to get rejected.
  • Blinded study
    • Wikipedia
      A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given. The opposite of a blinded study is an open label study.
  • Blinding
    • Wikipedia
      In a controlled trial: the process of preventing those involved in a trial from knowing to which comparison group a particular participant belongs. The risk of bias is minimized when as few people as possible know who is receiving the experimental intervention and who the control intervention. Participants, caregivers, outcome assessors, and analysts are all candidates for being blinded. Blinding of certain groups is not always possible, for example surgeons in surgical trials. The terms single blind, double blind and triple blind are in common use, but are not used consistently and so are ambiguous unless the specific people who are blinded are listed. (Also called masking.)
  • Block randomization
    • Randomization by a pattern to produce the required number of people in each group.
  • Book reviews
    • MeSH - Wikipedia
      Book reviews [MeSH - publication type]: works consisting of critical analyses of books or other monographic works.
  • Boolean operators
    • Words used when searching electronic databases. These operators are AND, OR, and NOT and are used to combine terms (AND/OR) or exclude terms (NOT) from the search strategy.
  • Booster sessions
    • Booster sessions are refresher sessions of the main content of formerly conducted interventions (i.e. school-based prevention programs).
  • Box plot
    • Wikipedia
      A visual display that summarizes data using a ``box and whiskers'' format to show the minimum and maximum values (ends of the whiskers), interquartile range (length of the box), and median (line through the box).
  • Budget
    • MeSH - Wikipedia
      A statement of the financial resources made available to provide an agreed level of service over a set period of time or to use them for a specific purpose.
      Detailed financial plans for carrying out specific activities for a certain period of time. They include proposed income and expenditures.
  • Burden of disease
    • Wikipedia
      The burden of disease is a measurement of the gap between a population's current health and the optimal state where all people attain full life expectancy without suffering major ill-health.
      Refers to the overall impact of diseases and injuries at the individual level, at the societal level, or to the economic costs of diseases.
      The total quantity of ill health caused by a particular disease or risk factor.
  • Burden of proof
    • Wikipedia
      The burden of proof in public health determines how evidence based practice is interpreted and applied.