# coefficient

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## coefficient

[ko″ĕ-fish´ent]**1.**an expression of the change or effect produced by the variation in certain variables, or of the ratio between two different quantities.

**2.**in chemistry, a number or figure put before a chemical formula to indicate how many times the formula is to be multiplied.

**absorption coefficient**absorptivity.

**Bunsen coefficient**the number of milliliters of gas dissolved in a milliliter of liquid at atmospheric pressure (760 mm Hg) and a specified temperature. Symbol, α.

**confidence coefficient**the probability that a confidence interval will contain the true value of the population parameter. For example, if the confidence coefficient is 0.95, 95 per cent of the confidence intervals so calculated for a large number of random samples would contain the parameter.

**correlation coefficient**a numerical value that indicates the degree and direction of relationship between two variables; the coefficients range in value from +1.00 (perfect positive relationship) to 0.00 (no relationship) to −1.00 (perfect negative or inverse relationship).

**diffusion coefficient**see diffusion coefficient.

**coefficient of digestibility**the proportion of a food that is digested compared to what is absorbed, expressed as a percentage.

**dilution coefficient**a number that expresses the effectiveness of a disinfectant for a given organism. It is calculated by the equation

*tc*=

^{n}*k*, where

*t*is the time required for killing all organisms,

*c*is the concentration of disinfectant,

*n*is the dilution coefficient, and

*k*is a constant. A low coefficient indicates the disinfectant is effective at a low concentration.

**linear absorption coefficient**the fraction of a beam of radiation absorbed per unit thickness of absorber.

**mass absorption coefficient**the linear absorption coefficient divided by the density of the absorber.

**phenol coefficient**see phenol coefficient.

**sedimentation coefficient**the velocity at which a particle sediments in a centrifuge divided by the applied centrifugal field, the result having units of time (velocity divided by acceleration), usually expressed in Svedberg units (S), which equal 10

^{−13}second. Sedimentation coefficients are used to characterize the size of macromolecules; they increase with increasing mass and density and are higher for globular than for fibrous particles.

## co·ef·fi·cient

(kō'ĕ-fish'ĕnt),**1.**The expression of the amount or degree of any quality possessed by a substance, or of the degree of physical or chemical change normally occurring in that substance under stated conditions.

**2.**The ratio or factor that relates a quantity observed under one set of conditions to that observed under standard conditions, usually when all variables are either 1 or a simple power of 10.

[L.

*co-*+*efficio*(*exfacio*), to accomplish]## coefficient

/co·ef·fi·cient/ (ko″ah-fish´int)**1.**an expression of the change or effect produced by variation in certain factors, or of the ratio between two different quantities.

**2.**a number or figure put before a chemical formula to indicate how many times the formula is to be multiplied.

**biological coefficient**the amount of potential energy consumed by the body at rest.

**correlation coefficient**a measure of the relationship between two statistical variables, most commonly expressed as their covariance divided by the standard deviation of each.

**linear absorption coefficient**in radiation physics, the fraction of a beam of radiation absorbed per unit thickness of the absorber.

**mass absorption coefficient**in radiation physics, the linear absorption coefficient divided by the density of the absorber.

**phenol coefficient**a measure of the bactericidal activity of a chemical compound in relation to phenol.

**sedimentation coefficient**the velocity at which a particle sediments in a centrifuge relative to the applied centrifugal field, usually expressed in Svedberg units (S), equal to 10−13 second, which are used to characterize the size of macromolecules.

**coefficient of thermal conductivity**a number indicating the quantity of heat passing in a unit of time through a unit thickness of a substance when the difference in temperature is 1°C.

**coefficient of thermal expansion**the change in volume per unit volume of a substance produced by a 1°C temperature increase.

## coefficient

[kō′efish′ənt]

Etymology: L,

*cum,*together with,*efficere,*to effecta mathematic relationship between factors that can be used to measure or evaluate a characteristic under specified conditions. Examples include Henry's law, which measures

**solubility coefficient;**Graham's law, which calculates**diffusion coefficient;**and the**oxygen-utilization coefficient,**which measures the amount of oxygen in a patient's venous blood in terms of the proportion of oxygen in his or her arterial blood.## coefficient

Vox populi A variable or factor which allows the calculation of a property or quantity of a substance under various conditions. See Absorption coefficient, Activity coefficient, Adsorption coefficient, Attenuation coefficient, Dice coefficient of similarity, Inbreeding coefficient, Intraclass correlation coefficient, Mass attentuation coefficient, Mass energy absorption coefficient, Octanol-water partition coefficient, Spearman's rank (order) correlation.## co·ef·fi·cient

(kō'ĕ-fish'ĕnt)**1.**The expression of the amount or degree of any quality possessed by a substance, or of the degree of physical or chemical change normally occurring in that substance under stated conditions.

**2.**The ratio or factor that relates a quantity observed under one set of conditions to that observed under standard conditions, usually when all variables are either 1 or a simple power of 10.

[L.

*co-*+*efficio*(*exfacio*), to accomplish]## coefficient

1. an expression of the change or effect produced by the variation in certain factors, or of the ratio between two different quantities.

2. in chemistry, a number or figure put before a chemical formula to indicate how many times the formula is to be multiplied.

**absorption coefficient**

1. the fraction of a beam of radiation that is absorbed in passing through a unit length of absorbing material.

2. a number indicating the volume of a gas absorbed by a unit volume of a liquid at 32°F (0°C) and at a pressure of 760 mmHg.

**alienation coefficient**

a measure of the

*lack*of association between two variables. Called also the coefficient of nondetermination.**Bunsen coefficient**

see absorption coefficient (2) (above).

**contingency coefficient**

a measure of association between qualitative assessments of two variables.

**correlation coefficient**

a measure of association which indicates the degree to which two or more sets of observations fit a linear relationship. Denoted by 'r', it can vary from −1.0 to 1.0.

**determination coefficient**

the coefficient of determination is the square of the correlation coefficient (r

^{2}). It describes the proportion of the variation of one of the correlated variables, explainable by the variation of the other variable. The value of the coefficient must lie between 0 and 1.**digestibility coefficient**

percentage of the food ingested that is absorbed.

**disarray coefficient**

the measure of the degree of discord between two variables.

**friction coefficient**

the effect that the material in a surface has on the frictional force created by the application of a force to the surface: S = f × N, where S = friction, f = friction coefficient, N = reaction to the vertical application of a given force. In a normal joint the f value is very small (0.008).

**coefficient of nondetermination**

see alienation coefficient.

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