Donald Reinertsen is the single most important intellectual influence on Anderson's Kanban Method. A product development consultant and author based in the United States, Reinertsen spent decades applying queueing theory and economics to the management of product development — a domain that most managers treated as immune to quantitative analysis. His two major books, "Managing the Design Factory" (1997) and "The Principles of Product Development Flow" (2009), established the theoretical framework that Anderson drew on most heavily when constructing the Kanban Method.
The winter 2005 conversation
The direct origin of the Kanban Method can be traced to a specific intellectual exchange. In winter 2005, following Anderson's initial kanban experiment at microsoft (the microsoft-xit-kanban-2004 event), Reinertsen persuaded Anderson to explore whether virtual kanban systems — not Toyota's physical card-based scheduling system but a WIP-limited pull system — could serve as the primary change mechanism for knowledge work organizations. This reframing was decisive. Where Anderson had initially thought of the Microsoft experiment as an application of Theory of Constraints in the spirit of eliyahu-goldratt, Reinertsen pointed him toward the richer analytical framework of queueing theory as the explanatory basis for why WIP limits improve flow.
Queueing theory as foundation
Reinertsen's central contribution to Anderson's thinking was the application of queueing theory — specifically the mathematical relationship between utilization rates, queue lengths, and cycle times — to knowledge work. The key insight, formalized in Little's Law and the M/M/1 queue model, is that as a system's utilization approaches 100%, wait times grow disproportionately (approaching infinity in the theoretical limit). This gives a precise, quantitative explanation for the deterioration of delivery performance that teams experience when they take on too much work simultaneously. Reinertsen had applied this analysis to product development; Anderson extended it to software engineering and knowledge work more broadly, making it the theoretical backbone of wip-limits as a practice.
"The Principles of Product Development Flow"
Reinertsen's 2009 book, published just as Anderson was completing the kanban-book, is the most rigorous treatment of flow management in product development. Its eight themes — economics, queues, variability, batch size, WIP, cadence and synchronization, fast feedback, and decentralized control — map almost exactly onto the practices of the Kanban Method. Anderson has cited this book as the closest intellectual companion to his own work. The foreword Reinertsen wrote for the kanban-book (2010) explicitly connected the two bodies of work and positioned Anderson's method within the queueing theory tradition.
Relationship in intellectual biography
Reinertsen's influence on Anderson is qualitatively different from Anderson's other intellectual sources (taiichi-ohno, eliyahu-goldratt, w-edwards-deming). Those figures provided frameworks that Anderson adapted for knowledge work; Reinertsen actively directed Anderson toward kanban systems as the vehicle for applying those frameworks. The corbis-kanban-experiment and the kanban-book bear Reinertsen's fingerprints throughout — in the economic framing of cost of delay, in the analysis of WIP and throughput, and in the insistence that classes-of-service be defined in terms of cost-of-delay profiles rather than arbitrary priority labels.