Jerry: What happened to my stereo? It’s all smashed up.— Seinfeld, The Package
Kramer: That’s right. Now it looks like it was broken during shipping and I insured it for $400.
Jerry: But you were supposed to get me a refund.
Kramer: You can’t get a refund. Your warranty expired two years ago.
Jerry: So we’re going to make the Post Office pay for my new stereo?
Kramer: It’s just a writeoff for them.
Jerry: How is it a writeoff?
Kramer: They just write it off.
Jerry: Write it off what?
Kramer: Jerry, all these big companies, they write off everything.
Jerry: You don’t even know what a writeoff is.
Kramer: Do you?
Jerry: No. I don’t.
Kramer: But they do, and they are the ones writing it off.
Jerry: I wish I just had the last twenty seconds of my life back.
Kanban is not exactly new to knowledge workers. It has been around since at least 2005. Yet even today when I hear someone say “yeah, we’re doing kanban” because they’ve decided to “get rid of iterations” or simply depict their requirements on digital cards, such as in Kanbanize or — may God help them — Jira, I feel like Jerry: “You don’t even know what a kanban is.”
I understand the reason for the confusion, though, as it has to do with the differing uses of the concept of a “card.” Kanban is roughly translated from Japanese as “signal card.” But a signal for what?
The first manifestation of kanban was in physical manufacturing, in which the card represented not the actual component or parts being built (like a tire or a box of screws) but a signal that the system had capacity to pull in the next batch of material. This “signal of capacity” was the key to just-in-time assembly, reducing inventory, improving flow and preventing overburdening of the system. (The card actually “recycles” itself back into the system.)
In knowledge work or “intangible goods” (e.g., software) delivery systems, we also want to obtain those lean benefits. The problem arises from misunderstanding the purpose of the cards we use: The venerable agile user story is expressed on a card (either physical or digital) — it’s one of the Three Cs! But the user story is a signal of demand and not capacity. Thus any card that we post on our work board is more analogous to the physical part in a manufacturing line (or, to use a different example, the visitors queueing at a museum or botanical garden). We need a virtual kanban to signal capacity and create a pull system.
We create these capacity-signaling virtual kanbans usually in one of two ways:
- Visual indicators of space (like an empty box)
- Explicit work-in-progress limit signs (like WIP=2)
So in knowledge work, it’s not the card but the available open spots for the card that are the kanbans! Signals of demand — work that someone wants to be done — are powerless to realize the benefits of flow. Rather, the only way we achieve a pull system is to signal capacity. Otherwise, it simply can’t and shouldn’t be called kanban in any meaningful way.