X-Nico

unusual facts about Standard deviation



68–95–99.7 rule

In statistics, the 68–95–99.7 rule, also known as the three-sigma rule or empirical rule, states that nearly all values lie within three standard deviations of the mean in a normal distribution.

SOFA Statistics

Nested tables can be produced with row and column percentages, totals, sd, mean, median, lower and upper quartiles, and sum.

Strictly standardized mean difference

In a primary screen without replicates, assuming the measured value (usually on the log scale) in a well for a tested compound is X i and the negative reference in that plate has sample size n N, sample mean \bar{X} N , median \tilde{X} N , standard deviation s N and median absolute deviation \tilde{s} N , the SSMD for this compound is estimated as

Vysochanskij–Petunin inequality

In probability theory, the Vysochanskij–Petunin inequality gives a lower bound for the probability that a random variable with finite variance lies within a certain number of standard deviations of the variable's mean, or equivalently an upper bound for the probability that it lies further away.


see also

Active contour model

Where G {\sigma} is a Gaussian standard deviation \sigma minima of this functional lie on zero-crossings of

Bessel's correction

In statistics, Bessel's correction, named after Friedrich Bessel, is the use of n − 1 instead of n in the formula for the sample variance and sample standard deviation, where n is the number of observations in a sample: it corrects the bias in the estimation of the population variance, and some (but not all) of the bias in the estimation of the population standard deviation.

Studentification

Studentization — adjustment of a statistic by dividing it by a sample-based estimate of its standard deviation.