Reconciling sourcing performance and P&L

Many CFOs share the same issue: 4 out 5 are facing difficulties reconciling the savings generated by initiatives on external spend and the financial impact on the P&L. Why? It just appears too complex and too resource-consuming to invest in. Yet, the supposed complexity shouldn’t serve as an impediment, knowing that external spend accounts for 30 to 80% of the total cost-base and as much of the cost optimization opportunity.