# variable

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## variable

[var´e-ah-b'l]something that changes; an attribute or property of a person, event, or object that is known to vary in a given study.

**dependent variable**in a mathematical equation or relationship between two or more variables, a variable whose value depends on those of others; it represents a response, behavior, or outcome that the researcher wishes to predict or explain.

**extraneous variable**a factor that is not itself under study but affects the measurement of the study variables or the examination of their relationships.

**independent variable**in a mathematical equation or relationship between two or more variables, any variable whose value determines that of others; it represents the treatment or experimental variable that is manipulated by the researcher to create an effect on the dependent variable.

## var·i·a·ble

(var'ē-ă-bĕl),**1.**That which is inconstant, which can or does change, as contrasted with a constant.

**2.**Deviating from the type in structure, form, physiology, or behavior.

[L.

*vario,*to vary, change, differ]## variable

/var·i·a·ble/ (var´e-ah-b'l)**1.**changing from time to time.

**2.**in mathematics, a symbol that represents an arbitrary number or an arbitrary element of a set.

## variable

(vâr′ē-ə-bəl, văr′-)*adj.*

**1.**

**a.**Likely to change or vary; subject to variation; changeable.

**b.**Inconstant; fickle.

**2.**

*Biology*Tending to exhibit genetic variation or variation in a physical trait: geographically variable color patterns.

**3.**

*Mathematics*Having no fixed quantitative value.

*n.*

Something that varies or is prone to variation.

**var′i·a·ble·ness**

*n.*

**var′i·a·bly**

*adv.*

## variable

[ver′ē·əbəl]

**1**a factor in an experiment or scientific test that tends to vary, or take on different values, while other elements or conditions remain constant. See also categoric variable, dependent variable, independent variable.

**2**an attribute of a person that is measurable and that varies (heart rate, age).

## variable

(1) Any attribute, phenomenon or event that can have different qualitative or quantitative values. Typically, a form of metadata goes with the variable, there is a variable definition that describes what is varying and there is a value for the variable. Variables are typically assessed in a clinical trial.(2) In Study Data Tabulation Model (SDTM), variables describe observations with roles that determine the type of information conveyed by the variable about each observation and how it can be used.

In SDTM, variables include specific subtypes used in clinical research: "study variable" in trial design refers to a variable to be captured on the case record form (CRF); an "assessment" is a study variable pertaining to the status of a subject/patient, is usually measured at a certain time and is usually not compounded significantly by combining several simultaneous measurements to form a derived assessment (e.g., BMI, or a result of statistical analysis); an "endpoint" is a variable that pertains to the trial objectives.

## variable

*noun*Epidemiology Any characteristic or attribute that can be measured. See Confounding variable, Continuous variable, Dependent variable, Independent variable, Instrumental variable, Intervening variable, Lurking variable, Natural variable, Predictor variable, Qualitative variable, Quantitative variable, Random variable.

## var·i·a·ble

(var'ē-ă-bĕl)**1.**That which is inconstant, which can or does change, as contrasted with a constant.

**2.**Deviating from the type in structure, form, physiology, or behavior.

[L.

*vario,*to vary, change, differ]## var·i·a·ble

(var'ē-ă-bĕl)That which is inconstant, which can or does change, as contrasted with a constant.

[L.

*vario,*to vary, change, differ]## variable,

*adj*

**1.**changing; able to vary in quantity or magnitude.

*n*

**2.**a characteristic that may assume several values.

**variable, continuous**,

*n*a variable for which it is possible to find an intermediate value between any two values. Continuous variables can be refined by more precise values. Length, weight, and time, and the points on a line are continuous variables.

**variable costs**,

*n*costs, such as dental service claims, that generally increase or decrease as the size and composition of the enrollment fluctuates.

**variable, dependent**,

*n*a variable whose value is consequent on change in the independent variable. The dependent variable is always the response or reaction to the independent variable. Also called

*criterion variable.*

**variable, discrete**,

*n*a variable that is expressed in whole units or mutually exclusive categories. Whole numbers and category designations such as sex and marital status are examples of discrete data.

**variable, independent**,

*n*the variable being studied that is manipulated or controlled by an experimenter. In a drug study an investigator may give several doses of a drug (independent variable) to determine the most effective, symptom-reducing (dependent variable) level.

**variables, control**,

*n.pl*those variables not being studied that are held constant so as not to influence the experimental outcome. Environmental conditions, intelligence quotients, and social and psychologic variables are examples of variables that must be controlled.

## variable

1. any type of measurement, quantitative or qualitative, of which a series of individual observations is made so that it has, as a principal characteristic, the potential for variability.

2. has the quality of variability.

**variable agent**

an agent in the cause of a disease which is capable of variation in intensity, e.g. weather, as contrasted to one that is not variable, e.g.

*Salmonella dublin*.**concomitant v's**

in experimental design these refer to factors that affect the dependent variable, but are not themselves influenced by the treatment (e.g. age of animal). The effect of concomitant variables can be removed by suitable experimental design or by including them in the model.

**continuous variable**

one in which all values within a given range are possible, e.g. birth weights of calves.

**variable costs**

costs which vary with the dimensions of the activity. Includes seed, fertilizer, teat dip, worm drench. Called also direct costs. See also fixed costs.

**dependent variable**

1. in statistics the variable predicted by a regression equation.

2. a variable which depends on other variables for its value.

**discontinuous variable**

see discrete variable (below).

**discrete variable**

one in which the possible values are not on a continuous scale, e.g. the number of sheep in a flock.

**endogenous variable**

dependent variable.

**exogenous variable**

independent or predetermined variable.

**independent variable**

one not dependent on other variables but capable of affecting dependent variables, thus an input variable.

**spatial variable**

a measurement relating to area or location.

**temporal variable**

one relating to chronological time.

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