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Indirect effect in a simple mediation model: The indirect effect constitutes the extent to which the X variable influences the Y variable through the mediator. In linear systems, the total effect is equal to the sum of the direct and indirect (C' + AB in the model above). In nonlinear models, the total effect is not generally equal to the sum ...
Calculus of variations is concerned with variations of functionals, which are small changes in the functional's value due to small changes in the function that is its argument. The first variation [l] is defined as the linear part of the change in the functional, and the second variation [m] is defined as the quadratic part. [22]
In mathematics, the direct method in the calculus of variations is a general method for constructing a proof of the existence of a minimizer for a given functional, [1] introduced by Stanisław Zaremba and David Hilbert around 1900.
In statistics, the Sobel test is a method of testing the significance of a mediation effect. The test is based on the work of Michael E. Sobel, [1] [2] and is an application of the delta method.
In the model below, the two exogenous variables (Ex 1 and Ex 2) are modeled as being correlated as depicted by the double-headed arrow. Both of these variables have direct and indirect (through En 1) effects on En 2 (the two dependent or 'endogenous' variables/factors). In most real-world models, the endogenous variables may also be affected by ...
The concepts of direct and inverse proportion lead to the location of points in the Cartesian plane by hyperbolic coordinates; the two coordinates correspond to the constant of direct proportionality that specifies a point as being on a particular ray and the constant of inverse proportionality that specifies a point as being on a particular ...
Symbolically, the method of concomitant variation can be represented as (with ± representing a shift): A B C occur together with x y z A± B C results in x± y z. ————————————————————— Therefore A and x are causally connected. Unlike the preceding four inductive methods, the method of concomitant ...
Indirect effects are interpreted similarly, with the magnitude of a specific indirect effect equaling the product of the series of direct effects comprising that indirect effect. The units involved are the real scales of observed variables’ values, and the assigned scale values for latent variables.