Table 1.

The top half of this table gives the definitions of all natural path-specific effects when there are two causally ordered mediators. There are eight versions (one level-0, three level-1, three level-2, and one level-3) of each of the four effects (direct, indirect through alone, indirect through alone, and indirect through both and ). The ones shown in bold are the ones defined in Sections Natural Direct Effects and Indirect Effects that Allow Decomposition. Note that the level-0 effects are those studied by Avin et al. (2005) and Albert and Nelson (2011). The bottom half of the table gives the definitions of the mediator-specific effects introduced in Section Mediator-specific natural effects

Path	Level	Effect	Definition
	0
	1
	1
Direct	1
(through )	2
	2
	2
	3
	0
	1
Indirect	1
through	1
	2
only	2
	2
	3
	0
	1
Indirect	1
through	1
	2
only	2
	2
	3
	0
	1
Indirect	1
through	1
both	2
and	2
	2
	3