Standard Deviation is an indicator of the 'spread' of the data (dispersion of a distribution). If mean is taken as the measure of central tendency of distribution, standard deviation tells us how much each value on an average is 'away' from the mean value (square-root of mean of squared deviations from the mean).
Thus, standard deviation is
In context of QSAR, descriptors having low standard deviation are not particularly relevant for regression modeling. Such descriptors don't have the required variance to be able to capture the variance in the property of interest that needs to be modeled. For classification scenario, however, descriptors with low standard deviation may capture some class or sub-class particularly well.
variance, coefficient of variation
Frank, H. and Althoen, S.C. "The variance and standard deviation." §C.4 in Statistics: Concepts and Applications Cambridge, Great Britain: Cambridge University Press, pp. 52-57, 1995.
Cite This As:
Dogra, Shaillay K., "Standard Deviation." From QSARWorld--A Strand Life Sciences Web Resource.