Week 2 Field session: The clipboard

Learning to record arrivals and services by hand, badly, and then learning what the errors were.

3 March 2027

Monday will have given you Little’s Law. This session is about the part that nobody ever bothers to write down, which is that those numbers have to come from somewhere in the first place, and that a human being with a clipboard is a fairly poor instrument.

What happens#

Twenty minutes, in the room. The observation sheet. Why it has the columns it has, why the time column is in seconds since you started rather than clock time, and why you tick rather than write.

Sixty minutes, in pairs, at the cafe queue downstairs. Both of you record the same queue independently for thirty minutes. You do not compare notes while you are doing it.

Forty minutes, back in the room. You compare. This is the session.

What you will find#

Pairs typically disagree on ten to twenty percent of arrivals in their first half hour. The disagreements are not random and that is the lesson. They cluster on the boundary cases, which are the same four every time.

• Someone joins, leaves, and rejoins.
• Two people arrive together and one of them orders.
• A customer is served without ever joining the line.
• The server does something that is not serving, and you have to decide whether the counter is busy or idle.

None of these have right answers. What matters is that you decide in advance and write the decision at the top of the sheet, and that you do not change it in week 6 because a different rule would make your numbers tidier.

Bring#

• A clipboard or a hard-backed notebook. Not a phone. You cannot tally and timestamp on a phone as fast as you can with a pen, and you will drop arrivals.
• Two pens.
• A watch or phone you can leave running without unlocking it.

What leaves the room#

You leave with a completed thirty-minute observation sheet, your partner’s sheet covering the same period, and one written rule for each of the four boundary cases. That rule sheet goes in the appendix of The Measured Queue.