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  2. Chi-squared distribution - Wikipedia

    en.wikipedia.org/wiki/Chi-squared_distribution

    In probability theory and statistics, the chi-squared distribution (also chi-square or -distribution) with degrees of freedom is the distribution of a sum of the squares of independent standard normal random variables. The chi-squared distribution is a special case of the gamma distribution and the univariate Wishart distribution.

  3. Chi distribution - Wikipedia

    en.wikipedia.org/wiki/Chi_distribution

    Chi distribution. In probability theory and statistics, the chi distribution is a continuous probability distribution over the non-negative real line. It is the distribution of the positive square root of a sum of squared independent Gaussian random variables. Equivalently, it is the distribution of the Euclidean distance between a multivariate ...

  4. Pearson's chi-squared test - Wikipedia

    en.wikipedia.org/wiki/Pearson's_chi-squared_test

    Usage. Pearson's chi-squared test is used to assess three types of comparison: goodness of fit, homogeneity, and independence. A test of goodness of fit establishes whether an observed frequency distribution differs from a theoretical distribution. A test of homogeneity compares the distribution of counts for two or more groups using the same ...

  5. Chi-squared test - Wikipedia

    en.wikipedia.org/wiki/Chi-squared_test

    Chi-squared distribution, showing χ2 on the x -axis and p -value (right tail probability) on the y -axis. A chi-squared test (also chi-square or χ2 test) is a statistical hypothesis test used in the analysis of contingency tables when the sample sizes are large. In simpler terms, this test is primarily used to examine whether two categorical ...

  6. Differential of a function - Wikipedia

    en.wikipedia.org/wiki/Differential_of_a_function

    e. In calculus, the differential represents the principal part of the change in a function with respect to changes in the independent variable. The differential is defined by where is the derivative of f with respect to , and is an additional real variable (so that is a function of and ). The notation is such that the equation.

  7. Standard normal table - Wikipedia

    en.wikipedia.org/wiki/Standard_normal_table

    Standard normal table. In statistics, a standard normal table, also called the unit normal table or Z table, [ 1 ] is a mathematical table for the values of Φ, the cumulative distribution function of the normal distribution. It is used to find the probability that a statistic is observed below, above, or between values on the standard normal ...

  8. Dimensionless numbers in fluid mechanics - Wikipedia

    en.wikipedia.org/wiki/Dimensionless_numbers_in...

    D. As a general example of how dimensionless numbers arise in fluid mechanics, the classical numbers in transport phenomena of mass, momentum, and energy are principally analyzed by the ratio of effective diffusivities in each transport mechanism. The six dimensionless numbers give the relative strengths of the different phenomena of inertia ...

  9. Kruskal–Szekeres coordinates - Wikipedia

    en.wikipedia.org/wiki/Kruskal–Szekeres_coordinates

    Kruskal–Szekeres coordinates on a black hole geometry are defined, from the Schwarzschild coordinates , by replacing t and r by a new timelike coordinate T and a new spacelike coordinate : for the exterior region outside the event horizon and: for the interior region . Here is the gravitational constant multiplied by the Schwarzschild mass ...