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  2. Contingency table - Wikipedia

    en.wikipedia.org/wiki/Contingency_table

    In other words, the two variables are not independent. If there is no contingency, it is said that the two variables are independent. The example above is the simplest kind of contingency table, a table in which each variable has only two levels; this is called a 2 × 2 contingency table. In principle, any number of rows and columns may be used ...

  3. Truth table - Wikipedia

    en.wikipedia.org/wiki/Truth_table

    A truth table has one column for each input variable (for example, A and B), and one final column showing all of the possible results of the logical operation that the table represents (for example, A XOR B). Each row of the truth table contains one possible configuration of the input variables (for instance, A=true, B=false), and the result of ...

  4. Combination - Wikipedia

    en.wikipedia.org/wiki/Combination

    Combination. In mathematics, a combination is a selection of items from a set that has distinct members, such that the order of selection does not matter (unlike permutations). For example, given three fruits, say an apple, an orange and a pear, there are three combinations of two that can be drawn from this set: an apple and a pear; an apple ...

  5. Linear combination - Wikipedia

    en.wikipedia.org/wiki/Linear_combination

    In mathematics, a linear combination or superposition is an expression constructed from a set of terms by multiplying each term by a constant and adding the results (e.g. a linear combination of x and y would be any expression of the form ax + by, where a and b are constants).

  6. Convolution of probability distributions - Wikipedia

    en.wikipedia.org/wiki/Convolution_of_probability...

    The convolution/sum of probability distributions arises in probability theory and statistics as the operation in terms of probability distributions that corresponds to the addition of independent random variables and, by extension, to forming linear combinations of random variables. The operation here is a special case of convolution in the ...

  7. Non-negative matrix factorization - Wikipedia

    en.wikipedia.org/wiki/Non-negative_matrix...

    The factorization is not unique: A matrix and its inverse can be used to transform the two factorization matrices by, e.g., [ 53 ] W B B − 1. If the two new matrices W ~ = and H ~ − 1 are non-negative they form another parametrization of the factorization. The non-negativity of W ~ and H ~ applies at least if B is a non-negative monomial ...

  8. Covariance - Wikipedia

    en.wikipedia.org/wiki/Covariance

    Covariance in probability theory and statistics is a measure of the joint variability of two random variables. [ 1 ] The sign of the covariance, therefore, shows the tendency in the linear relationship between the variables. If greater values of one variable mainly correspond with greater values of the other variable, and the same holds for ...

  9. Joint probability distribution - Wikipedia

    en.wikipedia.org/wiki/Joint_probability_distribution

    t. e. Given two random variablesthat are defined on the same probability space,[1]the joint probability distributionis the corresponding probability distributionon all possible pairs of outputs. The joint distribution can just as well be considered for any given number of random variables.