in business building

I recently completed a rapid innovation prices with a large retailer in South America. We drove 10-100 million USD in business impact value with 2 weeks of focused work. Specifically, we drove a significant reduction in operating cost, higher inventory turn and better customer NPS scores (possibly increased LTV). 
 
While we definitely drove this, it was a true partnership between us, the customer, and a committed and we’ll prepared account team. The customer gave us s 10/10 score.    
Following the process, we’ve been asked by the executive sponsor to look at an additional 8 funded special projects with our rapid prototyping Design Thinking Driven Development process.
 
The CxO is very enthusiastic and has asked for further evidence to sell SAPs process internally. With good reason, he’s asked for research that documents the value of Design Driven Development and Design Thinking. 
 
Here is some of the research I’ve found this far. There is ample evidence of Agile vs Waterfall, however, I’m still searching for something that documents the benefits to business with the front-loaded Design Thinking and rapid prototyping activities. 
A large majority of respondents (71 percent) stated that Design Thinking had improved the working culture particularly in the team. Innovation processes have become significantly more efficient for many users (69 percent) and the involvement of users occurs more frequently (48 percent). Cost savings (18 percent) or profit increase (29 percent) were less prominent.”
 
I’ll share as I find more research. Any tips would be most welcome.