to which different risks are mediated through other risks. Estimates of pathways of mediation are used to compute the burden attributable to aggregates of risk factors such as all behavioural risks or all risks combined. While we have conducted pooled cohort analyses to strengthen the assessment of mediation, this work was not yet ready for inclusion in this assessment. Pooled cohort studies have the advantage of providing a more standardised framework for assessing mediation across multiple risks. A related issue is the validation of the aggregation of risks in GBD. Pooled cohort studies will allow (in some circumstances) the opportunity to estimate if the aggregation of GBD RRs is as predictive of outcomes as suggested by the risk-by-risk analysis with mediation. Third, we have used the Das Gupta formula applied for each 5-year interval and for GBD Level 3 causes. Aggregations at higher levels of causes and for longer periods of time are based on these more granular analyses to guarantee consistency. Given the non-linear nature of the Das Gupta decomposition formula, however, alternative results are possible using different time periods and causes in the formula. Fourth, we have introduced the use of ensemble distributions to improve the empirical fitting
