Direct and Indirect Effects

TL;DR

This paper introduces a novel method for defining and estimating direct and indirect effects in both linear and nonlinear models without blocking paths, enhancing causal analysis techniques.

Contribution

It extends path-analytic methods to nonlinear and nonparametric models by defining path-specific effects without blocking remaining paths.

Findings

Provides conditions for consistent estimation from experimental data

Enables assessment of natural direct and indirect effects in complex models

Extends path analysis to nonlinear and nonparametric frameworks

Abstract

The direct effect of one eventon another can be defined and measured byholding constant all intermediate variables between the two.Indirect effects present conceptual andpractical difficulties (in nonlinear models), because they cannot be isolated by holding certain variablesconstant. This paper shows a way of defining any path-specific effectthat does not invoke blocking the remainingpaths.This permits the assessment of a more naturaltype of direct and indirect effects, one thatis applicable in both linear and nonlinear models. The paper establishesconditions under which such assessments can be estimated consistentlyfrom experimental and nonexperimental data,and thus extends path-analytic techniques tononlinear and nonparametric models.