# variance

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Related to variance: standard deviation, variance analysis

## deviation

[de″ve-a´shun]**1.**a turning away from the regular standard or course.

**2.**in ophthalmology, strabismus.

**3.**in statistics, the difference between a sample value and the mean.

**axis deviation**an axis shift in the frontal plane, as seen on an electrocardiogram. There are three types:

*Left,*from −30° to −90°;

*Right,*from +90° to +180°; and

*Undetermined,*which may be either extreme left or extreme right, from −90° to +180°.

**conjugate deviation**dysfunction of the ocular muscles causing the two eyes to diverge to the same side when at rest.

**sexual deviation**sexual behavior or fantasy outside that which is morally, biologically, or legally sanctioned, often specifically one of the paraphilias.

**standard deviation**(SD) the dispersion of a random variable; a measure of the amount by which each value deviates from the mean. It is equal to the square root of the variance. For data that have a normal distribution, about 68 per cent of the data points fall within (plus or minus) one standard deviation from the mean and about 95 per cent fall within (plus or minus) two standard deviations. Symbol σ.

**ulnar deviation**a hand deformity, seen in chronic rheumatoid arthritis and lupus erythematosus, in which swelling of the metacarpophalangeal joints causes the fingers to become displaced to the ulnar side. Called also ulnar drift. See illustration.

## var·i·ance

(var'ē-ăns),**1.**The state of being variable, different, divergent, or deviate; a degree of deviation.

**2.**A measure of the variation shown by a set of observations, defined as the sum of squares of deviations from the mean, divided by the number of degrees of freedom in the set of observations.

## variance

/var·i·ance/ (var´e-ans) a measure of the variation shown by a set of observations: the average of the squared deviations from the mean; it is the square of the standard deviation.## variance

[ver′ē·əns]

Etymology: L,

*variare***1**(in statistics) a numeric representation of the dispersion of data around the mean in a given sample. It is represented by the square of the standard deviation and is used principally in performing an analysis of variance.

**2**

Usage notes: nontechnical.

the general range of a group of findings. ## variance

A measure of the variability in a sample or population, which is calculated as the mean squared deviation (MSD) of the individual values from their common mean. In calculating the MSD, the divisor n is commonly used for a population variance and the divisor n-1 for a sample variance.## var·i·ance

(var'ē-ăns)**1.**The state of being variable, different, divergent, or deviate; a degree of deviation.

**2.**A measure of the variation shown by a set of observations, defined as the sum of squares of deviations from the mean, divided by the number of degrees of freedom in the set of observations.

## variance (s2)

(in statistics) the variation around the ARITHMETIC MEAN. It is calculated as the average squared deviation of all observations from their mean value. The square root of variance is the STANDARD DEVIATION## variance

one of the measures of the dispersion of data; the mean squared deviation of a set of values from the mean.

**additive genetic variance**

that portion of phenotypic variance which is due to the additive effect of genes (V

_{A}).**analysis of variance**

a statistical method for comparing values, expressed in terms of means or variance, of one or more variables in several subgroups of a population. Called also anova.

**non-additive genetic variance**

that portion of phenotypic variance which is due to epistatic interactions (V

_{I}) and dominance deviations (V_{D}).**non-genetic variance**

that portion of phenotypic variance which is due to non-genetic effects such as environment (V

_{E}).**phenotypic variance**

a measure of the extent to which individuals vary in their phenotype (V

_{P}). V_{P}= V_{A}+ V_{D}+ V_{I}+ V_{E}.**variance ratio distribution**

see f distribution.

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