Do you even know what a kanban is?

Jerry: What happened to my stereo? It’s all smashed up.
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.

— Seinfeld, The Package

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.)

This is not a kanban
In intangible-goods delivery systems, the card is not a kanban.

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.

4 thoughts on “Do you even know what a kanban is?

  1. Pingback: Kanban Myths – Matt Philip's Blog

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