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  2. List of mathematical constants - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical_constants

    For a lattice L in Euclidean space R n with unit covolume, i.e. vol(R n /L) = 1, let λ 1 (L) denote the least length of a nonzero element of L. Then √γ n n is the maximum of λ 1 (L) over all such lattices L. 1822 to 1901 Hafner–Sarnak–McCurley constant [118]

  3. Correlation coefficient - Wikipedia

    en.wikipedia.org/wiki/Correlation_coefficient

    The Pearson product-moment correlation coefficient, also known as r, R, or Pearson's r, is a measure of the strength and direction of the linear relationship between two variables that is defined as the covariance of the variables divided by the product of their standard deviations. [4]

  4. x̅ and R chart - Wikipedia

    en.wikipedia.org/wiki/X̅_and_R_chart

    In statistical process control (SPC), the ¯ and R chart is a type of scheme, popularly known as control chart, used to monitor the mean and range of a normally distributed variables simultaneously, when samples are collected at regular intervals from a business or industrial process. [1]

  5. Multidimensional scaling - Wikipedia

    en.wikipedia.org/wiki/Multidimensional_scaling

    An R-square of 0.6 is considered the minimum acceptable level. [citation needed] An R-square of 0.8 is considered good for metric scaling and .9 is considered good for non-metric scaling. Other possible tests are Kruskal’s Stress, split data tests, data stability tests (i.e., eliminating one brand), and test-retest reliability.

  6. Linear trend estimation - Wikipedia

    en.wikipedia.org/wiki/Linear_trend_estimation

    All have the same trend, but more filtering leads to higher r 2 of fitted trend line. The least-squares fitting process produces a value, r-squared (r 2), which is 1 minus the ratio of the variance of the residuals to the variance of the dependent variable. It says what fraction of the variance of the data is explained by the fitted trend line.

  7. R-value - Wikipedia

    en.wikipedia.org/wiki/R-value

    R-value (soils) in geotechnical engineering, the stability of soils and aggregates for pavement construction; R-factor (crystallography), a measure of the agreement between the crystallographic model and the diffraction data; R 0 or R number, the basic reproduction number in epidemiology; In computer science, a pure value which cannot be ...

  8. Proportionality (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Proportionality_(mathematics)

    The product of the x and y values of each point on the curve equals the constant of proportionality (k). Since neither x nor y can equal zero (because k is non-zero), the graph never crosses either axis. Direct and inverse proportion contrast as follows: in direct proportion the variables increase or decrease together.

  9. Notation in probability and statistics - Wikipedia

    en.wikipedia.org/wiki/Notation_in_probability...

    The α-level upper critical value of a probability distribution is the value exceeded with probability , that is, the value such that () =, where is the cumulative distribution function. There are standard notations for the upper critical values of some commonly used distributions in statistics: