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Concordant pair. In statistics, a concordant pair is a pair of observations, each on two variables, (X1, Y1) and (X2, Y2), having the property that. where "sgn" refers to whether a number is positive, zero, or negative (its sign). Specifically, the signum function, often represented as sgn, is defined as:
The usual order relation on the real numbers is antisymmetric: if for two real numbers and both inequalities and hold, then and must be equal. Similarly, the subset order on the subsets of any given set is antisymmetric: given two sets and if every element in also is in and every element in is also in then and must contain all the same elements ...
where E is the expected value operator. Notably, correlation is dimensionless while covariance is in units obtained by multiplying the units of the two variables. If Y always takes on the same values as X, we have the covariance of a variable with itself (i.e. ), which is called the variance and is more commonly denoted as the square of the ...
A marginal value is. a value that holds true given particular constraints, the change in a value associated with a specific change in some independent variable, whether it be of that variable or of a dependent variable, or. [when underlying values are quantified] the ratio of the change of a dependent variable to that of the independent variable.
Constant term. In mathematics, a constant term (sometimes referred to as a free term) is a term in an algebraic expression that does not contain any variables and therefore is constant. For example, in the quadratic polynomial, The number 3 is a constant term. [1]
e. In mathematics, a Cauchy (French: [koʃi]) boundary condition augments an ordinary differential equation or a partial differential equation with conditions that the solution must satisfy on the boundary; ideally so as to ensure that a unique solution exists. A Cauchy boundary condition specifies both the function value and normal derivative ...
A more familiar principal branch function, limited to real numbers, is that of a positive real number raised to the power of 1/2. For example, take the relation y = x 1/2, where x is any positive real number. This relation can be satisfied by any value of y equal to a square root of x (either positive or negative).
A closed half-space is the union of an open half-space and the hyperplane that defines it. The open (closed) upper half-space is the half-space of all (x1, x2, ..., xn) such that xn > 0 (≥ 0). The open (closed) lower half-space is defined similarly, by requiring that xn be negative (non-positive). A half-space may be specified by a linear ...