EcologyDictionary.org       Raising ecology awareness...
 EPA Terms of Environment Dictionary | EPA Glossary of Climate Change Terms | EU Bio-Glossary | Environmental Engineering Dictionary
 Home -› VARIANCE (2)

# VARIANCE (2) Environmental Engineering Dictionary
(Statistics) A measure of the spread or dispersion of a variable about its Mean or Arithmetic Mean value. The variance is calculated by taking the sum of the squares of the deviations, that is, the sum of the difference between the observed value and the series mean value, and dividing by the sample size (number of observations). The variance for a large data set (the population variance) is calculated as: s2 (sigma) = (xi :Â  x)2/n (sigma) = (xi :Â  x)2/n; where: xi is an individual observation; x is the mean of all observations; and n is the number of observations. xi is an individual observation; x is the mean of all observations; and n is the number of observations. For smaller data sets (typically less than 50) the sample variance (s2) is calculated by replacing n with n: 1 in this equation. The positive square root of the variance is called the Standard Deviation. Both the variance and the standard deviation are non-negative, by definition.

## Ecology Dictionary INDEX:

### List of Terms: Terms beginning with "A", Page 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

A: Page 1 of 73.

 A POSTERIORI CLA... A PRIORI CLASSIF... A&C A&I A&R A-HORIZON A-Scale Sound Le... A WPR AA AAEE AANWR AAP

 Your browser dosen't support javascripts.
Home   |   Dictionary   |   Translation   |   About Us   |   Contact Us Powered by Babylon - Translation Software
 Copyright © 2008 EcologyDictionary.org. All Rights Reserved.