Defective value streams

The term value stream is often misused and I have been as guilty as anyone in omitting the information flow part in my so-called value streams. This realization prompted me to do a bit of research into their origins and intent. The sources were mainly the Lean Enterprise Institute, an interview by Nigel Thurlow with John Shook, and the ISO 22468 standard for Value stream management.

The Lean Enterprise Institute was founded by James Womack who, together with Daniel Jones and Daniel Roos, wrote the bestseller The Machine That Changed the World. This book first articulated the principles of Lean production based on Toyota’s lean production system, also known as TPS. John Shook’s work with Toyota preceded and influenced The Machine That Changed the World and who, together with Mike Rother, wrote another Lean classic, Learning to See.

Value stream

A value stream is all of the actions required to bring a product (in a product family) from concept to launch (also known as the development value stream) and from order to delivery (also known as the operational value stream). These include actions to process information from the customer and actions to transform the product on its way to the customer. It takes a customer perspective, and clusters the actions in steps or processes that are demarcated by handovers.

The term value stream is borrowed from Toyota’s material and information flow, where material could equally have been translated as thing or good or product (according to John Shook, product is the best term), and where information is not the product (as in IT services) but the control information from the customer that helps understand what to do next.

Value stream map

A value stream map is visual tool and a useful simplification of messy reality that helps people to learn to see. It also applies to knowledge work that is more difficult to see than tangible products. Without the flow of information, a value stream map just a high-level process map.

A value stream map comprises four zones: information, process boxes, process data boxes, and metrics (often in the form of a lead time ladder). A value stream map can be enhanced with swimlanes per unit for the processes to make it easier to understand who does what.

Shook is keen to point out that the goal of value stream mapping is to help design a system with shorter lead times, and not to identify sources of waste, although this is often a byproduct. It is a valuable part of enhancing value creation and improving processes through iterative experimentation and continuous improvement.

Scope

A concern of mine is how to determine the scope of value stream maps. On the one hand, they should start and end with the customer, but do they extend across organizational borders and do they include the processes that create and provide the resources used by other processes?

Practical considerations help us deal with this dilemma, at least as far as maps are concerned. Maps are by definition simplifications of reality (“the map is not the territory” – Alfred Korzybski) and you have to omit less important parts until a useful level of simplification is achieved.

This means that the size of the value stream will determine what can be included on a single map (for example the creation of a product), and what has to be described on another map (for example the provision of a resource that is used to create the product).

A hierarchical approach can also be used, where a high-level map shows the overall customer journey, with links to more detailed sub-maps focusing on specific sub-processes, like resource creation.