A model explaining product design as a stack of decisions built on top of a stack of knowledge. With apologies to Jesse James Garrett.

A diagram containing layers stacked on top of each other

I’ve sketched lots of messy diagrams like this over the years. Sometimes in conversation with people who want to learn design. And my emphasis then was on skills. And other times I’ve sketched something similar when discussing where we should go next in a design project. In that case the emphasis is on the different flavours of knowledge: what we know, and what we need to decide.

Over time I realised the link between both types of conversations: Be hired as a designer and you’re taking on responsibility to make design decisions of various flavours. Your skills are your abilities to make—or facilitate—those decisions soundly.

I used to draw it horizontally like a value stream, showing how products are shaped first by research, then modelling etc. I added feedback loops to show that it’s not linear but it always had a misleading sequential feel. Then I rediscovered Jesse James Garrett’s Elements of User Experience diagram, and I realised a stack was a much better way to think about this. There isn’t a time dependency between the layers, but there is a logical dependency. If something in a lower layer changes, it can dislodge the layers above. If the layers above don’t map well to the layers below, you’ll find yourself with UX debt, and a poor experience.

I’m making a distinction between problem and solution spaces here too, inspired by Indi Young’s writing on that topic. A lot of our energy must be directed to understanding the problem space independent of our solutions, if we want to be innovative.

Usually, products are designed by many people, including people without ‘designer’ in their title. User researchers are skilled at finding user needs. Product managers are skilled at product & service strategy. And engineers and architects have a huge influence on the conceptual model. But in a small team one person might be doing most of this solo, even without realising it. After all, products are always designed, intentionally or not.

Use this diagram to think:

  • Do we have a solid foundation for our project? Have we skipped a layer and introduced UX debt? (The conceptual model is often overlooked)
  • Which layer is most of our uncertainty currently in?
  • Does our team have skills to attack the necessary layers?
  • What layer do I most enjoy working in?