I came across this great writing, which tackles 2 complex topics, causal mediation, and then this g-formula, not an easy feat...
They present a sweeping overview of current 'causal' mediation understanding, wonderfully summarized in some tables, especially 1:
and 2 (a bit 'thicker' for newcomers...)
* Note that g-formula has been incorporated in Stata (SAS too), see: http://www.stata-journal.com/article.html?article=st0238 .
Wang, A., & Arah, O. A. (2015). G-computation demonstration in causal mediation analysis. European Journal of Epidemiology, 30(10), 1119-1127. doi: 10.1007/s10654-015-0100-z http://link.springer.com/article/10.1007/s10654-015-0100-z
Daniel RM, De Stavola BL, Cousens SN. gformula: estimating causal effects in the presence of time-varying confounding or mediation using the g-computation formula. Stata J. 2011;11(4):