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  2. Free variables and bound variables - Wikipedia

    en.wikipedia.org/wiki/Free_variables_and_bound...

    n is a free variable and k is a bound variable; consequently the value of this expression depends on the value of n, but there is nothing called k on which it could depend. In the expression ∫ 0 ∞ x y − 1 e − x d x , {\displaystyle \int _{0}^{\infty }x^{y-1}e^{-x}\,dx,}

  3. Softmax function - Wikipedia

    en.wikipedia.org/wiki/Softmax_function

    One can normalize input scores by assuming that the sum is zero (subtract the average: where =), and then the softmax takes the hyperplane of points that sum to zero, =, to the open simplex of positive values that sum to 1 =, analogously to how the exponent takes 0 to 1, = and is positive.

  4. Bayesian vector autoregression - Wikipedia

    en.wikipedia.org/wiki/Bayesian_vector_autoregression

    Vector autoregressions are flexible statistical models that typically include many free parameters. Given the limited length of standard macroeconomic datasets relative to the vast number of parameters available, Bayesian methods have become an increasingly popular way of dealing with the problem of over-parameterization. As the ratio of ...

  5. Hat notation - Wikipedia

    en.wikipedia.org/wiki/Hat_notation

    In statistics, a circumflex (ˆ), called a "hat", is used to denote an estimator or an estimated value. [1] For example, in the context of errors and residuals , the "hat" over the letter ε ^ {\displaystyle {\hat {\varepsilon }}} indicates an observable estimate (the residuals) of an unobservable quantity called ε {\displaystyle \varepsilon ...

  6. Estimator - Wikipedia

    en.wikipedia.org/wiki/Estimator

    "Single value" does not necessarily mean "single number", but includes vector valued or function valued estimators. Estimation theory is concerned with the properties of estimators; that is, with defining properties that can be used to compare different estimators (different rules for creating estimates) for the same quantity, based on the same ...

  7. Least squares - Wikipedia

    en.wikipedia.org/wiki/Least_squares

    The result of fitting a set of data points with a quadratic function Conic fitting a set of points using least-squares approximation. In regression analysis, least squares is a parameter estimation method based on minimizing the sum of the squares of the residuals (a residual being the difference between an observed value and the fitted value provided by a model) made in the results of each ...

  8. Estimation statistics - Wikipedia

    en.wikipedia.org/wiki/Estimation_statistics

    Many significance tests have an estimation counterpart; [26] in almost every case, the test result (or its p-value) can be simply substituted with the effect size and a precision estimate. For example, instead of using Student's t-test , the analyst can compare two independent groups by calculating the mean difference and its 95% confidence ...

  9. Eight-point algorithm - Wikipedia

    en.wikipedia.org/wiki/Eight-point_algorithm

    The basic eight-point algorithm is here described for the case of estimating the essential matrix .It consists of three steps. First, it formulates a homogeneous linear equation, where the solution is directly related to , and then solves the equation, taking into account that it may not have an exact solution.