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  2. Weighted sum model - Wikipedia

    en.wikipedia.org/wiki/Weighted_Sum_Model

    In decision theory, the weighted sum model (WSM), [1] [2] also called weighted linear combination (WLC) [3] or simple additive weighting (SAW), [4] is the best known and simplest multi-criteria decision analysis (MCDA) / multi-criteria decision making method for evaluating a number of alternatives in terms of a number of decision criteria.

  3. List of price index formulas - Wikipedia

    en.wikipedia.org/wiki/List_of_price_index_formulas

    This is the formula that was used for the old Financial Times stock market index (the predecessor of the FTSE 100 Index). It was inadequate for that purpose. It was inadequate for that purpose. In particular, if the price of any of the constituents were to fall to zero, the whole index would fall to zero.

  4. Ramanujan's sum - Wikipedia

    en.wikipedia.org/wiki/Ramanujan's_sum

    In number theory, Ramanujan's sum, usually denoted c q (n), is a function of two positive integer variables q and n defined by the formula = (,) =,where (a, q) = 1 means that a only takes on values coprime to q.

  5. Aggregate function - Wikipedia

    en.wikipedia.org/wiki/Aggregate_function

    Sum; Others include: Nanmean (mean ignoring NaN values, also known as "nil" or "null") Stddev; Formally, an aggregate function takes as input a set, a multiset (bag), or a list from some input domain I and outputs an element of an output domain O. [1] The input and output domains may be the same, such as for SUM, or may be different, such as ...

  6. Sturges's rule - Wikipedia

    en.wikipedia.org/wiki/Sturges's_rule

    Sturges's rule [1] is a method to choose the number of bins for a histogram.Given observations, Sturges's rule suggests using ^ = + ⁡ bins in the histogram. This rule is widely employed in data analysis software including Python [2] and R, where it is the default bin selection method.

  7. Abel's summation formula - Wikipedia

    en.wikipedia.org/wiki/Abel's_summation_formula

    Abel's summation formula can be generalized to the case where is only assumed to be continuous if the integral is interpreted as a Riemann–Stieltjes integral: ∑ x < n ≤ y a n ϕ ( n ) = A ( y ) ϕ ( y ) − A ( x ) ϕ ( x ) − ∫ x y A ( u ) d ϕ ( u ) . {\displaystyle \sum _{x<n\leq y}a_{n}\phi (n)=A(y)\phi (y)-A(x)\phi (x)-\int _{x ...

  8. Numerical method - Wikipedia

    en.wikipedia.org/wiki/Numerical_method

    Let (,) = be a well-posed problem, i.e. : is a real or complex functional relationship, defined on the cross-product of an input data set and an output data set , such that exists a locally lipschitz function : called resolvent, which has the property that for every root (,) of , = ().

  9. PRESS statistic - Wikipedia

    en.wikipedia.org/wiki/PRESS_statistic

    It is calculated as the sum of squares of the prediction residuals for those observations. [ 1 ] [ 2 ] [ 3 ] Specifically, the PRESS statistic is an exhaustive form of cross-validation , as it tests all the possible ways that the original data can be divided into a training and a validation set.