Please, no comments like “You can’t manage what you can’t measure.” That’s bunk. Always has been. Always will be. And to support my harsh stance on this ridiculous statement, I’ll cite none other than Albert Einstein, who kept a sign on his Princeton office wall saying:
“Not everything that matters can be measured. But not everything that can be measured matters.”
In many cases, trying to measure growth in share of customer stemming from improved customer experience triggered by introduction of Outside-In process quickly becomes a fool’s errand. We can get halfway there by measuring improvement in customer experience (although doing so requires a very high level of research expertise, beyond simple NPS scores). But even these measures are subject to influence from contextual changes. And freeing changes in share of wallet from contextual changes defies research. Hell, we can rarely measure the thickness of the wallet, so how do we calculate the share?
So what are the alternatives to direct measurement? Or does anyone want to argue with Einstein? 
Based on our experience, the most effective way in most situations is establishing intuitive “cause & effect” relationships where certain actions well-performed will enhance customer experience in ways that should broaden relationships – or directly trigger additional business from customers, as should be the case for new products/services. While research can’t statistically measure the effects in most cases, they can validate the connections using Kano studies (not VOC, C-Sat or especially not NPS).
Not precise enough for you? Then you don’t belong measuring anything to do with people, customers included.
