SD | S.D. | standard deviation
DEFINITION measure of how close or how far data points are from their average, or deviates from the mean - which, in a data sample, is estimated as the positive square root of the sum of the squares of the deviations between the observations and the mean of the data, divided by one less than the total number of observations REFERENCE COM-EN, based on: <BR>IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8 http://goldbook.iupac.org/S05911.html [4.12.2009]
COMMENT The standard deviation is the positive square root of the <i>variance</i> [ IATE:1681483 ]. <BR>The variance and the closely-related standard deviation are measures of how spread out a distribution is. In other words, they are measures of variability.<BR>The variance is computed as the average squared deviation of each number from its mean.