Skip to content
Leantensify Learn

What could be causing this, other than the thing I already suspect?

Generate possible causes across six categories, mark which ones you have actually checked, and see when the diagram is telling you more about the room than about the problem.

Cause & Effect (Fishbone) · analyze · White Belt · free, no account needed

Use this when

  • A team has one favourite explanation and no evidence for it
  • You need to widen the search before choosing what to measure
  • The same problem keeps returning after each fix

Cause & Effect (Fishbone)

sandbox

One thing that is happening, with a number if you have one. Not what to do about it.

Pick the set that fits the work.

People8

Skills, handovers, staffing levels, who was available — the SYSTEM around people, not their effort.

  • Pickers forget to check the SKU against the tote label
  • Not enough training for agency staff
  • New starters shadow for one day; the standard says three
  • Night shift covers two zones, so picks are interleaved
  • Handovers between shifts are verbal
  • Agency staff rotate weekly
  • Peak-hour targets reward speed at the pick face
  • Supervisors are pulled onto the floor during peaks

Method1

The way the work is done: sequence, standards, instructions, what happens when the standard does not fit.

  • Pick list sorts by SKU, the racking is sorted by supplier

Machine1

Equipment, tooling, software, capacity, maintenance state.

  • Handheld scanners drop connection in aisle 7

Material1

Inputs and their variation: suppliers, batches, specification, storage.

  • Two SKUs share a near-identical package design

Measurement0

How you know: the gauge, the definition, who records it, whether two people agree.

    Environment0

    Physical and organisational conditions: layout, temperature, noise, deadlines, incentives.

      11 possible causes, 0 checked against data

      empty categoryNothing under Measurement. How you know: the gauge, the definition, who records it, whether two people agree. An empty bone is an unasked question — sometimes the honest answer is that this category is not involved, and sometimes it is the one nobody in the room has visibility of.

      empty categoryNothing under Environment. Physical and organisational conditions: layout, temperature, noise, deadlines, incentives. An empty bone is an unasked question — sometimes the honest answer is that this category is not involved, and sometimes it is the one nobody in the room has visibility of.

      one bone dominates73% of the causes are under People. That can be right, but it is more often a sign the room shares one department's view. Whoever works next to the other categories is the person to ask.

      cause blames a person"Pickers forget to check the SKU against the tote label" — "Pickers forget" blames a person for the outcome. Ask what about the work made that easy to do or hard to avoid. The answer is the cause; the person is where you noticed it.

      cause is a solution"Not enough training for agency staff" — "training for" is a solution verb. Written as a missing solution, it cannot be tested; written as a mechanism it can. "Not enough training" becomes "the standard changed in March and nobody was told", which you can go and check.

      nothing verifiedNone of the 11 causes has been checked against data. That is a fine place to be at the end of the session and a dangerous place to be at the start of the next one: a fishbone generates hypotheses, and the longest bone is the one the room talked about most, not the one that matters most.

      How this is calculated

      No statistics and no score. A fishbone generates hypotheses; it produces no evidence, and the longest bone is the one the room talked about most rather than the one that matters most.

      • The effect is stated, and does not already contain a solution.
      • There are enough causes that the diagram was worked rather than started.
      • Every category has been asked, and no single bone carries most of it.
      • No cause is written as a missing solution — “not enough training” cannot be tested.
      • No cause blames a person rather than naming a mechanism.
      • At least one cause has been checked against data.

      Source: Ishikawa, K. (1990), Introduction to Quality Control, Ch. 3; Tague, N. (2005), The Quality Toolbox, 2nd ed.

      Saved runs can be attached to a project deliverable as evidence. Both what you entered and what the tool computed are stored, so the result can be checked again later.

      How this is calculated

      Structural check, no statistics and no score. Verifies that the effect is stated and free of solutions, that enough causes exist to have been worked rather than started, that every category was asked and no single bone carries more than half, that no cause is written as a missing solution or as blame, and that at least one cause has been checked against data.

      Source: Ishikawa, K. (1990), Introduction to Quality Control, Ch. 3; Tague, N. (2005), The Quality Toolbox, 2nd ed., cause-and-effect diagram.

      Learn the method