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Glossary of terms used in health research - V

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  • Validated instrument
    • One way of ensuring the quality of data collected by instrument (questionnaire) is to use only those which have been validated. A validated instrument is one which has undergone a validation procedure to show that it accurately measures what it aims to do, regardless of who responds, when they respond, and to whom they respond. Elements of a validation procedure may include the examination of reliability, the comparison of results with other sources of data, the translation and reverse translation to reduce ambiguity, the examination of feasibility: acceptability, time needed to respond, cost etc. as well as the examination of variation in response due to data inquiry methods (self-administered, personal interview, telephone interview etc.).
  • Validation
    • Wikipedia
      Validation in the pharmaceutical and medical device industry is defined as the documented act of demonstrating that a procedure, process, and activity will consistently lead to the expected results. It often includes the qualification of systems and equipment. It is a requirement for Good Manufacturing Practices and other regulatory requirements.
  • Validation studies
    • MeSH
      Research using processes by which the reliability and relevance of a procedure for a specific purpose are established.
      Validation studies [MeSH - publication type]: works consisting of research using processes by which the reliability and relevance of a procedure for a specific purpose are established.
  • Validity
    • Wikipedia
      The degree to which a result (of a measurement or study) is likely to be true and free of bias (systematic errors). Validity has several other meanings, usually accompanied by a qualifying word or phrase; for example, in the context of measurement, expressions such as ‘construct validity’, ‘content validity’ and ‘criterion validity’ are used.
      An expression of the degree to which the surveillance data measure the true incidence of cases in the population.
  • Values
    • Wikipedia
      Concepts used to explain how and why things matter. Values are involved wherever we distinguish between things good and bad, better or worse. Values are characterized as scientific, professional, cultural, social, personal, family, religious, and organic (for example, health). Scientific values include: objectivity, accuracy, generalizability, validity and others. Values are pervasive in epidemiology and public health.
  • Variability
    • Wikipedia
      The extent to which a group of scores varies or is spread out. This is usually described by a descriptive statistic such as the range or standard deviation.
  • Variable
    • A factor that differs among and between groups of people. Variables include patient characteristics such as age, sex, and smoking, or measurements such as blood pressure or depression score. There can also be treatment or condition variables, e.g. in a childbirth study, the length of time someone was in labor, and outcome variables. The set of values of a variable in a population or sample is known as a distribution.
      Any characteristic or attribute that can be measured.
  • Variable cost
    • Wikipedia
      The cost associated with a program or intervention that varies with the size of the programme or the number of patients treated with the intervention. Cost items such as consumables would be variable costs.
  • Variance
    • Wikipedia
      A measure of the variation shown by a set of observations, equal to the square of the standard deviation. It is defined as the sum of the squares of deviations from the mean, divided by the number of observations minus one.
      A measure of the dispersion shown by a set of observations, defined by the sum of the squares of deviations from the mean, divided by the number of degrees of freedom in the set of observations.
  • Verification bias
    • Results of a diagnostic test influence whether patients are assigned to an intervention group.
  • Vertical equity
    • Refers to the “unequal treatment of unequals”. This is a more problematic concept because it is difficult to decide how unequal people should be in terms of the amounts of resources devoted to them or how much more access we should provide for some over others. For example, one may think that we should devote more health resources to those who are more socially deprived, but how do we decide how much more? What if people in more deprived groups do not gain as much health from interventions as those in better off groups? Judgments about what to do when faced with such questions will always be subjective.
  • Very low birth weight
    • MeSH
      Birth weight less than 1,500 grams.
      An infant whose weight at birth is less than 1,500 grams (3.3 lbs), regardless of gestational age.
  • Very preterm birth
    • A live birth or stillbirth that takes place after at least 20 but less than 32 completed weeks of gestational age.
  • Virtues
    • MeSH - Wikipedia
      Character traits—not skills nor techniques—that make an individual a good professional practitioner, and help her to do her work well. For epidemiologists, the virtues of excellence, integrity, honesty, self effacement, and prudence are important examples. Virtue is not easily taught but may be learned by example from mentors.
      Character traits that are considered to be morally praiseworthy.
  • Virulence
    • MeSH
      The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors.
  • Virulence factors
    • MeSH
      Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that effect the ability of the microorganism to invade and colonize a host.
  • Vital statistics
    • MeSH - Wikipedia
      Demographic data on births, deaths, fetal deaths, marriages and divorces.
      Systematically tabulated information about births, marriages, divorces, and deaths, based on registration of these vital events.
      Used for general articles concerning statistics of births, deaths, marriages, etc.
  • Vulnerable populations
    • MeSH
      Persons who, by reason of diminished competence or decision making capacity, lack of power or social standing, fragile health, deprivation, or limited access to basic needs including health care, are vulnerable to coercion, abuse, exploitation, discrimination, imposition of unjust burdens of research, and poorer health outcomes. Similar acts may be construed to be coercive in a vulnerable population that would not be in other, well situated populations. Includes children, institutionalized persons, the frail, and those with mental disorder, as well as those on the margins of society.
      Individuals whose willingness to volunteer in a clinical trial may be unduly influenced by the expectation, whether justified or not, of benefits associated with participation, or of a retaliatory response from senior members of a hierarchy in case of refusal to participate. Examples are members of a group with a hierarchical structure, such as medical, pharmacy, dental, and nursing students, subordinate hospital and laboratory personnel, employees of the pharmaceutical industry, members of the armed forces, and persons kept in detention. Other vulnerable subjects include patients with incurable diseases, persons in nursing homes, unemployed or impoverished persons, patients in emergency situations, ethnic minority groups, homeless persons, nomads, refugees, minors, and those incapable of giving consent.
      Groups of persons whose range of options is severely limited, who are frequently subjected to coercion in their decision making, or who may be compromised in their ability to give informed consent.
      Also called vulnerable subjects.