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  2. Variance - Wikipedia

    en.wikipedia.org/wiki/Variance

    In probability theory and statistics, variance is the expected value of the squared deviation from the mean of a random variable. The standard deviation (SD) is obtained as the square root of the variance. Variance is a measure of dispersion, meaning it is a measure

  3. Statistical dispersion - Wikipedia

    en.wikipedia.org/wiki/Statistical_dispersion

    Variance (the square of the standard deviation) – location-invariant but not linear in scale. Variance-to-mean ratio – mostly used for count data when the term coefficient of dispersion is used and when this ratio is dimensionless, as count data are themselves dimensionless, not otherwise. Some measures of dispersion have specialized purposes.

  4. Probability distribution - Wikipedia

    en.wikipedia.org/wiki/Probability_distribution

    Variance: the second moment of the pmf or pdf about the mean; an important measure of the dispersion of the distribution. Standard deviation: the square root of the variance, and hence another measure of dispersion.

  5. Deviation (statistics) - Wikipedia

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

    The sum of squared deviations is a key component in the calculation of variance, another measure of the spread or dispersion of a data set. Variance is calculated by averaging the squared deviations. Deviation is a fundamental concept in understanding the distribution and variability of data points in statistical analysis. [1]

  6. Standard deviation - Wikipedia

    en.wikipedia.org/wiki/Standard_deviation

    Using words, the standard deviation is the square root of the variance of X. The standard deviation of a probability distribution is the same as that of a random variable having that distribution. Not all random variables have a standard deviation.

  7. List of mathematical abbreviations - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical...

    def – define or definition. deg – degree of a polynomial, or other recursively-defined objects such as well-formed formulas. (Also written as ∂.) del – del, a differential operator. (Also written as.) det – determinant of a matrix or linear transformation. DFT – discrete Fourier transform.

  8. Variance function - Wikipedia

    en.wikipedia.org/wiki/Variance_function

    In statistics, the variance function is a smooth function that depicts the variance of a random quantity as a function of its mean.

  9. Homogeneity and heterogeneity (statistics) - Wikipedia

    en.wikipedia.org/wiki/Homogeneity_and...

    Plot with random data showing heteroscedasticity: The variance of the y-values of the dots increases with increasing values of x. In statistics, a sequence of random variables is homoscedastic (/ ˌ h oʊ m oʊ s k ə ˈ d æ s t ɪ k /) if all its random variables have the same finite variance; this is also known as homogeneity of variance ...