Lesson 15 of 23 · 7 min read
Did it hold? The Check in PDCA
In Lean: the Check in PDCA
Builds on: Every change is an experiment
In one minute
A change that works in its first week can quietly slip back by the end of the month. So the check is not one look but several: soon after the change, to catch early problems, and again later, once a busy period has tested it. Each look has three honest answers: it held, it partly held, or the old way came back. All three are useful, because each tells you what to do next.
The idea
Did it hold? (in Lean: the check in PDCA) sounds like a single moment. In practice changes fail in typical ways at typical times, so one look is not enough.
- In the first week, people forget the new way, the change clashes with something nobody foresaw, or a tool setting is missing.
- Within a few weeks, the change survives ordinary weeks but not the unusual one: month-end, a holiday, the owner away.
- By about a month, the change has met most of the situations of an ordinary month.
There is no fixed rule for when to look. One workable rhythm is about a week, two weeks and a month, which catches each kind. A single look right after the change mostly tells you that people remembered it that week.
Illustrative, no real data
| Example fix | Day 7 | Day 14 | Day 30 |
|---|---|---|---|
| Fix A | Held | Held | Held |
| Fix B | Held | Held | Partly |
| Fix C | Held | Partly | Reverted |
A reverted fix counts nothing.
At each look, check what the prediction named, in the work itself: the queue, the returned forms, the requests that still arrive by email. Impressions are a poor guide, because people who worked on a change want it to have worked.
There are three answers (the check result), and each leads somewhere.
Held. The problem stayed away and the new way is still being done. Keep looking until the last check, because a change that held at a week can still slip by a month. After the last check, write it down as the normal way (lesson 16).
Partly. Some of it works. The useful question is where it does not. Partly usually points at a second branch of the cause, or at a group the change did not reach: one region, one kind of request, the weeks when the owner is away. Make the next small change aimed at that part, as a new cycle. Do not guess what share of the problem is gone; if you can count it, count it, and if not, "partly" is enough.
Reverted. The old way came back. That is not a wasted month and not someone's failure. It tells you the change did not fit the work, or the cause was not the one you thought. Ask what happened at the moment it slipped: what made the old way easier just then? Take that fact back to the cause. If the problem is still there, report it again so its history stays with it.
Answer honestly. "Held" feels like success, and the change may have been someone's idea, so there is a pull to say it. A "held" that is not true hides the problem again. A "reverted" given honestly is the start of a better countermeasure. A team where "reverted" is an ordinary answer learns faster than one where every change is declared a success.
Example
Illustrative example, not a real company.
An IT team changes how laptops are ordered for new starters: HR raises the request when the contract is signed, not on the starter's first day.
At one week: held. That week's starters had their laptops on day one.
At two weeks: held again.
At one month: partly. Starters hired through an agency arrived without laptops. Their contracts are signed with the agency, so HR never sees a signing date and nothing triggers the request. A second branch of the cause. The next cycle: for agency starters, the request is raised when the start date is confirmed.
Had the team looked only once, at one week, it would have declared success and missed the agency branch entirely.
Common mistakes
- Checking once, right after the change. Early success says little about the busy weeks ahead.
- Answering "held" out of loyalty to the idea. Look at the work, not at how you feel about the change.
- Treating "reverted" as someone's fault. Ask what made the old way easier, not who went back to it.
Words to know
- Did it hold? (in Lean: the check in PDCA): looking, at set intervals, at whether a change still works.
- Held: the problem stayed away and the change is still being done.
- Partly: some of it works; find where it does not.
- Reverted: the old way came back; take what you learned back to the cause.
Check your understanding
Try it on your own work
Describe one recurring task that wastes your time, and see these ideas applied to it.
Worksheet for this lesson: PDCA Template, Countermeasure Plan Template (free download, no sign-up).
Where this comes from
Checking a change against what was expected, and returning to it over time, is the Check of the plan-do-check-act cycle at the heart of the Lean tradition's way of improving work.