This should come as no surprise, as, according to Jeff Sutherland, the creator of Scrum,
"Scrum was the first concrete implementation of lean thinking to software development that allowed organizations of all types and sizes to start up lean teams in a couple of days using a standard pattern that was easily understood. What was hard was explaining why and how to implement the pattern to generate continuous quality and productivity improvement.
Today, the writing and courses from Mary and Tom Poppendieck provide a proven set of principles that organizations can use to adapt tools, techniques, and methods to their own specific unique contexts and capabilities. Now we can explain how to use Scrum to lean out software development."
Lean provides an essential foundation for anyone wishing to employ Scrum in the organization.
Many of the dramatic improvements in Scrum are due more to changes in team structure than to the (iterative, team-led) processes that the team follows. Understanding what affects improvement is important both to improve the confidence of developers in these practices and to increase the likelihood such practices will be adopted by teams in the first place. This understanding can be used to create standard practices, practices that all teams should be aware of and follow. We need to look at the systems we follow and not just expect each individual developer will do the right thing based on their motivation alone. While they may try to do the right thing, not knowing certain basic standards will result in lost opportunities. Lean thinking can give us insights into how to find these best practices to improve software development processes. Understanding the connection between Lean and Agile is essential to enjoying the benefits of Scrum beyond the single team (Phase 2) to the rest of the enterprise.
 Implementing Lean Software Development: From Concept to Cash, p. xviii, Mary and Tom Poppendieck.