Lean product development: principles, set-based design, A3s

Lean product development applies lean thinking to designing new products: create knowledge early, keep design options open and make work flow smoothly. The focus is on learning faster, not on drawing faster.

Allen Ward set out much of the thinking in his book Lean Product and Process Development. It was published in 2007 after his death and completed by Durward Sobek. This guide covers the principles, set-based design, the chief engineer system, batch size, A3s and how the approach relates to lean startup.

Key takeaways

Lean product development treats design as a knowledge-creation process, not just a production of drawings.

Set-based concurrent engineering keeps several design options open until data shows which one fits.

Toyota's chief engineer system gives one person overall responsibility for a product's concept and success.

Smaller batches and a steady cadence reduce waiting in design work.

A3 reports and trade-off curves communicate decisions on a page and make learning reusable.

What is lean product development?

Lean product development is a method for creating new products that treats the main output of design as knowledge. The drawings and prototypes are carriers of that knowledge.

Ward drew on his study of Toyota. He argued that lean product and process development differs from lean manufacturing because the work is uncertain and creative. You cannot just remove waste from a fixed procedure, because the procedure itself is being invented. See our lean methodology overview for the wider context.

People also search for 'lean new product development'. The terms describe the same field.

What are the principles of lean product development?

The principles center on creating knowledge, seeing value from the customer's view, keeping options open, and keeping work flowing. Different authors list them differently, so treat any list as a summary.

Ward's book describes ideas such as defining value and front-loading the design process to explore alternatives. It also covers a leveled flow of work and a strong chief engineer, and it stresses standardization that supports flexibility, not rigidity.

These ideas overlap with the Toyota Production System and share its respect for people and focus on waste. In development, the waste is often rework, waiting for decisions and unused information.

What is the learning loop in lean product development?

The learning loop is a cycle of forming a question, testing it, and recording what you learned so the next project can reuse it. Recorded knowledge builds up over time.

In a typical loop, a team states a design question and builds a quick test or model. It then reads the result and captures it in a short document. That document is then available to future teams.

This is close to the PDCA cycle, applied to design. Teams that do not record what they learned tend to repeat the same mistakes on the next product.

What is set-based concurrent engineering?

Set-based concurrent engineering is a design approach in which a team explores several options at once and narrows them gradually as evidence arrives. It contrasts with point-based design, where you pick one option early and refine it.

Say a team must choose a housing material for a device. A point-based approach picks one early. A set-based approach tests three, discards those that fail on cost or strength, and chooses from the survivors. The example is illustrative.

Studies of Toyota by Allen Ward, Durward Sobek and colleagues, including a 1999 article in the Sloan Management Review, described this set-based practice. It costs more effort early but reduces expensive late changes.

What is the chief engineer system?

The chief engineer system is Toyota's practice of giving one senior engineer overall responsibility for a vehicle's concept, design and commercial success. The chief engineer leads through technical authority, not formal power over staff.

The chief engineer writes the concept, holds the vision for the customer and resolves trade-offs between functions. Specialist departments still own their technical expertise.

The idea is to avoid a product that is a compromise assembled by committee. Outside Toyota, product owners or lead architects play a comparable role, though the match is never exact.

How do cadence, flow and batch size apply to design?

In design work, a regular cadence, a visible flow and small batches reduce the time that ideas sit waiting. Large batches of drawings handed over at once hide problems until late.

A cadence means synchronized, regular events, such as a fortnightly design review. Teams know when decisions get made, so work does not stall waiting for an ad hoc meeting.

Reducing batch size means releasing design information in smaller pieces, early and often. Say a team sends a complete drawing set after eight weeks and finds an error. If they had sent a partial set every week, they would have found it sooner. The numbers are illustrative.

A kanban board can make design flow visible and limit work in progress. Our guide to lean thinking explains the flow principle.

How do A3s and trade-off curves support decisions?

A3 reports and trade-off curves put the reasoning behind a design choice on one page, so teams can discuss and reuse it. The A3 format was developed at Toyota.

An A3 states the background, the current situation, the options and the recommended action on a single sheet. It makes the thinking visible so others can challenge it.

A trade-off curve plots how a design parameter affects a performance measure. For example, it might show how wall thickness changes both weight and strength. Teams use such curves to decide with data, not opinion.

Both tools capture knowledge in a form that outlives the project.

How does lean product development relate to lean startup?

Lean product development and lean startup both aim to learn quickly and reduce waste, but they start from different places. The first grew from engineering at Toyota. The second grew from testing new businesses under extreme uncertainty.

Lean startup emphasizes validated learning about customers through a minimum viable product. Lean product development emphasizes building technical knowledge through set-based design and reuse.

A team can combine them. Use startup methods to test whether customers want the product, then use set-based design and A3s to develop it. The MVP tools category lists software that supports early testing.

Frequently asked questions