Photo by Hans-Peter Gauster
Big Ideas

How Creating a Design Funnel Can Lead to Better Design Decisions

One of the ultimate goals of a design process is to help designers and engineers navigate the design space with confidence.

The design space meaning the collection of potential solutions that are still in consideration or possible given your information, constraints, assumptions, decisions, and requirements. In other words: when the design space is wide, there are many possibilities for paths forward that are still open for consideration; when the design space is narrow, you are focused on few or one single path forward.

As designers, the width of the design space is a critical variable to observe, because it is directly tied with the level of detail in design activities and how easy it is to adapt to new information.

The Design Funnel

As we learn more, find more constraints, set more assumptions, make more design decisions, and focus more on detail, the narrower the design-space becomes. This is often called the design funnel, which captures the notion that over time the design space gets narrower as early ambiguous problem spaces are clarified into focused, detailed designs.

Early in the development process, the design space is often widely constrained and open to a variety of solutions and paths forward. In these wide and early phases, creative exploration is encouraged and design activities are broad and flexible. As a result, activities in the early part of the process are often a bit more vague or open to interpretation, allowing teams to move fast and make changes.

At the end of projects, design teams are focused on a well-defined product, with tested architectures, detailed designs, thorough product requirements, and documented decisions. In these narrow and later phases, critical review and detailed thinking are encouraged, so design activities are more focused and detail oriented.

As a result, activities later in the process tend to take longer, require more attention, and can be broken into more finite details in a process. A good process helps funnel the design space at an appropriate rate and encourages the right level of focus in design activities.

Even when mess is present, the design space narrows over time. Wandering and exploration in common in the beginning, but at the end the design is clear and focused.

Encouraging Divergence Early

The design funnel not only embodies the narrowing of design space from ambiguity to clarity, it also indicates how acceptable divergence is to the development effort. Divergence being course corrections from mistakes and new information, as well as creative exploration of alternative paths. And it’s important to remember that divergence is a great thing for a design.

Divergence is when creative thinking is at its best, opportunities for design improvements are high, and design teams learn quickly. However, as a rule of thumb, as a project matures, divergence becomes more costly. Not only due to the sunk cost, but also as projects mature and designs become more detailed, the time associated with developing increases and the cost of prototyping increasing detailed designs also drastically increases. Therefore, the idea is if you make mistakes (you will), if you have to change plans at some point (you will), if you have to make course corrections (you will), and if you want to explore creatively for other options (you should), it is best to do it earlier in the process than later.

Designers are encouraged to fail early and fail often for this exact reason. With every failed prototype and explorative brainstorming session to fix it we learn more and are less likely to fail later.

A good process helps encourage designers to make your mistakes early and explore your options early, to avoid course corrections late in the project when costs are high.

In the beginning of the process, mistakes and changes are O.K. and even encouraged. Later in the process, mistakes and changes are costly.

A Funnel of Ever Smaller Funnels

In reality, the design process is not one big smooth funnel of convergence. Design teams are constantly learning new things, discovering unknowns, and reevaluating design decisions. Divergence is bound to happen and therefore, we cannot expect every next step in the design process to be more detailed and focused than the one before it. As a result, convergence happens in a series of smaller and smaller funnels. Usually, this funnel is focused around the end of a phase of work, sprint, or deliverable when design teams focus on driving to bring a design to a required level.

Following the trend of the overall, average design funnel, these funnels get progressively smaller over the course of the development period. The output of each subsequent funnel is more detailed and more feature complete design or prototype than the one before it. Similarly, as the design progresses, we expect the divergence at the mouth of each funnel to get smaller and smaller.

Processes should expect and design in an understanding of these increasingly funnels.

Convergence happens in a series of progressively tighter ‘funnels.’ With each funnel, the divergence at the input is a bit less and the output deliverable is a bit more detailed and complete.

Creative Divergence and Focused Convergence

The design space and focus of a design team are repeatedly fluctuating wider and narrower in divergent and convergent phases on all scales. These repeating divergence-convergence cycles respond to project needs and drive project focus.

When the design direction seems ambiguous or design problems seem under-defined, teams need to learn more information, repeatedly try and fail, and explore relevant paths for hopes of discovering both promising and unpromising directions. In doing so, we allow a divergence away from a previously focused vision and set our sights on new information, stronger constraints, smarter assumptions, or better design options.

Creativity, curiosity, and adaptation reign in divergence. This is where design teams allow designs and requirements to shift to react to new information and better design alternatives.

Convergent phases are the funnels and course corrections that focus and solidify the design. Typically following a period of divergence or added information, convergence focuses the team on the details of a design and pushes development forward towards a deliverable or testable state. In the push, the goal is not only to tackle the known challenges in the details, but also to uncover unknown obstacles and test assumptions, constraints, and decisions.

Engineering and problem-solving reign in convergence. This is where detailed design decisions are made, prototypes are built, and products find embodiment.

As we explore, learn, test, and decide the design space fluctuates between divergent exploration and convergent focus. Eventually, the space settles steady as we progress to production.

Synthesis and Planning, Embodiment and Evaluation

The transitioning moments between divergence and convergence are critical moments in a development process. While there are many factors that affect when we diverge and when we converge, shifting from divergence to convergence almost always includes some form of synthesis and planning, and shifting from convergence to divergence almost always includes some form of embodiment and evaluation.

Synthesis being the composition of new information that guide design decisions and planning being the subsequent reactions to synthesized information, such as changing product requirements and shifting design direction. Together synthesis and planning is how we take in new information, figure out how to adapt, and implement the necessary course corrections that will direct us back towards the right solution and right product.

On the opposite side of the cycle, embodiment of a design is typically the output of the focused and detailed work that comes after a design direction is converged upon, and evaluation is how we decide if what we’ve focused on is actually the right direction.

These outputs are the visual or physical embodiments of the design, such as sketches, visual models, or prototypes, that we intend to test and evaluate against predetermined criteria. Together embodiment and evaluation is how we explain our design decisions, test our designs, and decide whether our design is headed in the right direction.

Synthesizing information enables convergence by giving reason to focus rather than maintain a broad solution space. Embodiments, such as prototypes, open up conversation around the design decisions and spur creative exploration to improve the design.

Design Activities Throughout the Process

As the design space fluctuates, the design progresses, and the focus of the design team shifts, the types and volume of design activities change in scope, purpose, detail, and effort. A flexible design process means that these activities are not incremental or scripted in order, but rather a potential and relevant design activities that can be undertaken.

In some cases, design teams can look to the process for ideas of what design activities that they could or should be doing.