Nov 11 2011

From scancards to “personal kanbans” and Ybry charts

Professionals know that their productivity drops when they take on too many concurrent projects. An engineer whose attention is split across 15 projects doesn’t contribute effectively to any. But it happens because supervisors keep piling on assignments without regard to this phenomenon. Over the years, cures have been proposed under different names, all aiming to cap work in process.

About 1982, a colleague showed me the system he used to manage what he was working on. It was called the Scancard System, and it used the hardware  in Figure 1. The cards were square, with 3 1/4-in sides and borders of different colors. They came with letter-size card pocket plastic boards that you could insert into 3-ring binders, keep on your desk or pin to a wall.

Figure 1. The Scancard System

He used it with one column for his backlog of things to do, one column for work in process, and one column for completed items. It was a paper-based system but, at the time, so was almost everything we did. It gave you visibility, it capped the number of items you were working on at one time, and moving cards from one column to the next was an effective metaphor for the flow of your work. The ads showed smartly dressed managers using their scancard systems in meetings. I went for it and used it for years, until I had a project with a company that used another system and switched to fit in.

Fast forward to 2011. Scancard Systems is out of business, and I hear of a system called “Personal Kanban,” that is focused on providing visibility and limiting work in process, using a white board and Post-Its as in Figure 2:

Figure 2. “Personal Kanban”

I put quotes around the name because I find it to be little more than a feat of vocabulary engineering, leveraging the buzz around a feature of Toyota’s production control system to repackage ideas that have little to do with it, are very simple and have been around for a long time. A software developer visiting a factory may see a similarity with Toyota’s Kanbans, but it escapes me.

Of course, if, as in Figure 2,  it is on a white board, you can’t carry it with you to a meeting or share it in your network. The Personal Kanban website advertizes an iPhone app called iKan, that I can’t find on Apple’s App Store. On the other hand, Leankit Kanban offers a web-based application with an iPhone version that looks very much like a team to-do list management system. It looks most useful if your work can be perceived as a collection of independent activities, which happens if each Post-It is for a whole project or for a prospect in a sales cycle. But it would not fit if each Post-It were for a task within a project, with precedence constraints or iterations between tasks.

Another limitation of such a status board is that is only shows current status, as compared, for example, with the Ybry chart of Figure 3, which shows the complete history of each project by using a line for each project rather than a card. Like the status board, it assumes that all project go through the same sequence of phases.

Figure 3. Ybry chart for projects going through the same sequence of phases

Ybry charts were invented by Charles Ybry in 1846 for railroad scheduling, and are still used for that purpose. See Edward Tufte’s Envisioning Information, pp. 107-110. The work-combination charts used in Lean operator job design are a variation on this method, as explained in Working with Machines, pp. 133-154.

By • Management • 10 • Tags: , , , ,