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  2. Square root - Wikipedia

    en.wikipedia.org/wiki/Square_root

    Square root. Notation for the (principal) square root of x. For example, √ 25 = 5, since 25 = 5 ⋅ 5, or 52 (5 squared). In mathematics, a square root of a number x is a number y such that ; in other words, a number y whose square (the result of multiplying the number by itself, or ) is x. [1] For example, 4 and −4 are square roots of 16 ...

  3. Variance - Wikipedia

    en.wikipedia.org/wiki/Variance

    The use of the term n − 1 is called Bessel's correction, and it is also used in sample covariance and the sample standard deviation (the square root of variance). The square root is a concave function and thus introduces negative bias (by Jensen's inequality), which depends on the distribution, and thus the corrected sample standard deviation ...

  4. Standard deviation - Wikipedia

    en.wikipedia.org/wiki/Standard_deviation

    The standard deviation of a random variable, sample, statistical population, data set, or probability distribution is the square root of its variance. It is algebraically simpler, though in practice less robust , than the average absolute deviation .

  5. Root mean square deviation - Wikipedia

    en.wikipedia.org/wiki/Root_mean_square_deviation

    In general, a lower RMSD is better than a higher one. However, comparisons across different types of data would be invalid because the measure is dependent on the scale of the numbers used. RMSD is the square root of the average of squared errors.

  6. Standard error - Wikipedia

    en.wikipedia.org/wiki/Standard_error

    Hence the estimator of ⁡ becomes + ¯, leading the following formula for standard error: ⁡ (¯) = + ¯ (since the standard deviation is the square root of the variance). Student approximation when σ value is unknown

  7. Unbiased estimation of standard deviation - Wikipedia

    en.wikipedia.org/wiki/Unbiased_estimation_of...

    Since the square root is a strictly concave function, it follows from Jensen's inequality that the square root of the sample variance is an underestimate. The use of n − 1 instead of n in the formula for the sample variance is known as Bessel's correction , which corrects the bias in the estimation of the population variance, and some, but ...

  8. Probability distribution - Wikipedia

    en.wikipedia.org/wiki/Probability_distribution

    A probability distribution is a mathematical description of the probabilities of events, subsets of the sample space. The sample space, often represented in notation by Ω ,{\displaystyle \ \Omega \ ,}is the setof all possible outcomesof a random phenomenon being observed. The sample space may be any set: a set of real numbers, a set of ...

  9. Range (statistics) - Wikipedia

    en.wikipedia.org/wiki/Range_(statistics)

    In descriptive statistics, the range of a set of data is size of the narrowest interval which contains all the data. It is calculated as the difference between the largest and smallest values (also known as the sample maximum and minimum). [1] It is expressed in the same units as the data. The range provides an indication of statistical dispersion.