Demonstrating the impact of marketing when performance is the result of cross-functional efforts requires three elements:

• Show performance of shared impact metrics. Whether the goal is increased deal velocity, better renewal rates or improved customer loyalty, you need to demonstrate that the impact metrics marketing invests in are, in fact, improving.
• Provide proof of marketing participation. You need to prove that when marketing tactics are accepted by target audiences, impact metrics improve. If marketing isn’t involved, it will be uncomfortably difficult to assert any type of marketing influence over that performance improvement.
• Present evidence that performance metrics change as marketing participation changes. Evidence of marketing impact requires a comparison. Some deal cycles may have light levels of marketing interaction, some may have heavy levels, and some may have no marketing interaction at all. When you compare what improvements take place when marketing is present to what happens when marketing is not, you can develop reasonable proof that marketing is making a difference.