Measuring Customer Engagement: It’s Not Easy and It Takes Time
How you assign your point values may seem arbitrary at first, but you will need to work through this iteratively, looking at control cells wherever you can isolate them. For a more scientific approach, run a regression analysis on the customer file with revenue as the dependent variable and the number and types of touches as the independent variables. The more complete your customer contact data is, the lower your p value and the more descriptive the regression will be in identifying the contribution of each element.
As with any methodology, this one is only as good as the data you're able to put into it, but don't be discouraged if your data is not perfect or complete. Even in an imperfect world, this exercise will get you closer to a holistic view of customer engagement.