There is a verifiable difference between the two, and it does not depend on how many times someone asked "why."
The 5 whys is the technique that questions a chain of causes: you ask "why?" of every answer until you reach a condition the company can change.
It works in a professional practice, in a fifteen-person family business and in a hundred-person organization: who answers changes, the temptation to stop at the first answer does not.
In Italy, 81.2% of manufacturing companies are under personal or family control [5]: a chain that ends on a name costs twice.
The 5 whys are not counted, they are verified: the chain is only as good as the evidence behind each answer, and it stops when it reaches a condition the company can change, not a person to reprimand.
This article walks the chain through a complete case, the typical deviation at each step and the three ways the technique fails.
Replacing the part or changing the condition: what the 5 whys really ask
Are replacing the broken part and changing the condition that makes it break the same action or two different actions?
They are two different actions, and the first is the one that brings the problem back: without following the chain all the way down, you "would just replace the fuse or the pump shaft," and the failure would recur within a few months [1].
Faced with a recurring failure, the sequence is almost everywhere the same: you replace the part, close the report, and the following month it starts all over again.
The 5 whys technique was born to break exactly that sequence, by asking "why?" of every answer you get.
This section sets out what the technique asks, where it comes from and what it should be distinguished from.
The development of the technique is attributed to Toyoda Sakichi for Toyota Industries [2]; it was Ohno who put it in writing, stating that he adapted it from that habit of observation [1].
The original example is a stopped machine: blown fuse, unlubricated bearing, pump not supplying oil, worn shaft, missing chip strainer [1].
The boundaries are in the links: root cause analysis is the family of methods this technique belongs to, and the Ishikawa diagram is the sister technique that opens up causes in breadth, where the 5 whys digs deep into just one.
Compared with brainstorming, what changes is the evidence, which here supports each answer before the next step (short definition in the glossary).
Compared with holding someone to account, what changes is the target: "didn't do it" is followed by the question of what prevented them from doing it.
Hence the criterion that closes every chain in this article: a root cause is the condition that, once eliminated or kept under control, prevents or reduces the chance of the event happening again [7].
Replacing the part closes the report, changing the condition closes the problem: what remains is to understand when five steps are really needed.
When five questions are enough and when there is more than one cause
Do a problem with a single chain of causes and a problem with six families of causes call for the same method?
No, and you can see the difference before you start: when there are already three or four plausible answers to the first "why," the technique alone is not enough, and Serrat's methodological note for the Asian Development Bank explicitly points to the Ishikawa diagram [2].
The 5 whys cost a sheet of paper and twenty minutes, which is both their strength and the reason they get used even where they are not needed.
This section gives three conditions to check before calling anyone in: the problem recurs and can be measured, the chain of causes is plausibly linear, and the data needed to verify each answer can be reached within the day.
If one of the three is missing, the section tells you where to go instead: to the fishbone when there is more than one cause, to the complete process when the problem is serious or cuts across several departments.
The three conditions are written like this.
- the problem recurs and can be counted: how many times, over what period;
- at the first "why" there are one or two plausible answers, not five;
- the evidence to verify the answers consists of documents or numbers that already exist in the company.
The referrals, in order: to the Ishikawa diagram when plausible answers are many and come from different people [2], to the guide to business problem solving when the choice is about the process, to root cause analysis for the family of methods, to organizational problems in companies when the symptom is widespread.
Either way, the chain lives inside processes that already exist: continuous improvement hosts it in the analysis phase.
Once the three conditions are met, you follow the chain all the way through.
A complete 5 whys example: from the relabeled batch to the cause in five questions
Four batches relabeled by hand in one month: did it happen because someone failed to check, or because nobody was supposed to check?
The difference between the two answers is not one of tone but of level: the first closes the chain at the first step, the second takes it all the way to a procedure written when only one product ran on the line.
Each "why" holds only if the answer can be checked against a document or a number: where the evidence is missing, the chain stops being an analysis and becomes an opinion written in five lines.
The case is hypothetical and built for teaching purposes: a twenty-five-person family business that packages food products for other brands, six SKUs on the same line, and a business owner who moves between the office and the shop floor several times a day.
The symptom is measurable — in the last month, four batches out of sixty were relabeled by hand, about nine hours of unscheduled work, because the printed expiration date did not match the product specification sheet.
The table walks through the five steps with the evidence and the typical deviation at each one.
The same five questions, in a professional practice, start from a file sent back by the client and arrive at the same kind of condition: a step that nobody is responsible for confirming.
| Why | Answer | Evidence supporting it | Typical deviation at this step |
|---|---|---|---|
| Why were four batches relabeled? | The label showed an expiration date different from the one on the product specification sheet | The four batches that were held, with label and specification sheet side by side | "The packer didn't check": the chain ends on a person at the first step and the problem remains |
| Why was the date different? | The labeling machine still had the shelf life of the product run before | The product changeover log: in all four cases the previous batch had a longer shelf life | "The machine is old": a cause outside the company's control, which on top of that does not explain why it happens on four batches and not on sixty |
| Why was the previous setting still there? | At changeover the parameter is set by hand and no step confirms its value before startup | A hands-on test of the changeover: seven parameters to set, only one with a confirmation | Stopping here and evaluating recipe management software: an intervention decided before knowing what the cause is |
| Why does no step confirm it? | The changeover procedure says "set the line parameters" without listing them or saying who checks them | The text of the procedure in force | "Lack of training": an answer that cannot be checked against any document and points to nothing to change |
| Why is the procedure generic? | It was written when only one SKU ran on the line and was not revised when there became six | The procedure's revision date, earlier than the introduction of the new SKUs | Stopping at the fourth why because "we already know the answer": this is the point where the only cause you can act on gets lost |
The root cause is the changeover procedure, written for one SKU and never revised when there became six.
It passes the test: once that condition is corrected the event does not recur, and it is a condition of the company, not of a person [7].
Step 2 hid a fork: there were two plausible answers — the leftover setting and a supply of labels preprinted by the customer — and the procedure calls for following both until the data rule one out [2].
The product changeover log rules out the second, and that branch closes on a document.
Who is there, how long it takes, where it gets written: how to run a 5 whys session
Do a chain written by the people who saw the problem and one written in the office the following week arrive at the same cause?
Rarely: the Asian Development Bank note is clear about the low repeatability of the result — different teams applying the 5 whys to the same problem arrive at different causes [2].
The technique requires no software and no budget, and that is exactly why the way the session is run is the variable that determines its quality.
This section covers who needs to be in the room, how long it takes, where the chain gets written and the rule that holds it together.
The procedure comes down to five moves.
- Who is there: whoever saw the problem, whoever deals with it downstream, and whoever can change the condition — in the case of the line, the line supervisor, the packing operator and the business owner.
- The problem statement, written and agreed on before starting, with the number and the period.
- One answer at a time, attached to the one that generated it, with all plausible answers followed, not just the first.
- On-the-spot verification of the answer just given, before moving on [2].
- Stopping, when a further "why" adds no useful information, and moving on to action.
Three conditions matter more than the procedure — an accurate statement, honest answers, determination to get to the bottom [2] — and the second is the most delicate in a family business.
If the people answering fear the consequences, the chain stops one level too early and the sheet comes out clean and wrong.
The sheet is minimal: the "5 Whys Form" has five rows, the evidence column next to each answer and the verification field at the bottom.
Twenty to forty minutes are enough, on the shop floor rather than in the meeting room.
If the session changes a way of working, the notes end up in a standard operating procedure, not in an email.
The people who saw the problem bring evidence, the person writing in the office brings a memory: that is where the two chains part ways.
From cause to action: what has to change so the problem does not come back
Did a session that ends with "from now on let's be more careful" and one that ends with an extra line in the procedure find the same cause?
No: the second found a condition that can be changed, the first stopped at a behavior — and for the more than one hundred thousand Italian organizations with a certified quality system [6], reviewing the effectiveness of the intervention is not a good habit but a requirement they have signed up to [4].
The chain produces a cause, not an action: the transition between the two is where most sessions get lost.
This section sets three minimum requirements for the action that comes out of a 5 whys — it changes a document, a step or a tool; it has an owner and a date; it has an indicator already written down and a verification date.
It closes with the question most companies never ask: sixty days later, has that number gone down?
And with the only honest conclusion if it has not — the chain stopped too early.
The three requirements, applied to the line case.
- it changes a document, a step or a tool: a changeover checklist with the seven parameters and the signature of the person who verifies them;
- it has an owner and a date: the line supervisor, by the end of the current month;
- it has an indicator already written down and a verification date: batches relabeled in the month, reviewed at sixty days.
The review is not a refinement: the quality management systems standard requires you to evaluate the need for action on the causes so that the nonconformity does not recur, and to review the effectiveness of that action [4].
In Italy there were 101,426 active ISO 9001 certificates as of December 31, 2024 [6].
How to record the action and when a nonconformity should be opened are covered under nonconformity management.
The action does not eliminate the problem: it reduces the probability that it returns, and you can only say so after verification.
The three ways the technique fails: the culprit, the single branch, the missing evidence
A chain that ends with a person's name and one that ends with the name of a document: which of the two found a cause?
Only the second, and the Asian Development Bank note says so plainly: when faced with a problem, the temptation to blame others or external events is strong, while the root cause is almost always closer to home [2].
The three ways the technique fails are not execution errors but three specific points at which the chain stops being an analysis, and they are the same in a three-person practice and in a hundred-person company.
The first is the culprit: the chain ends on whoever made the mistake instead of on the condition that made the mistake possible.
The second is the single branch: you follow only one answer when there were three plausible ones, and come out with one cause where there were two.
The third is the missing evidence: an answer that no document and no number can confirm, and which therefore cannot even be corrected.
The culprit. You recognize it by the shape of the answer: a person and a negative verb, "didn't check," "forgot."
The fix is one more question — why that person was unable to do what they were supposed to — repeated until the answer points to a document, a tool or a missing step [2].
The single branch. You recognize it after the fact: at the first or second "why" three answers were given, and only one is left on the sheet.
The fix is to follow them all, each attached to the one that generated it, and to rule them out with data rather than with the consensus of the room [2].
The healthcare safety literature notes that the name "root cause" suggests there is only one, and that the linear narrative of some techniques in the family — the 5 whys is named explicitly — masks reconstructions involving several interacting factors [3].
The observation comes from mandatory, repeated investigations of adverse events in healthcare.
If after the second step more than two branches remain open, the referral is to the Ishikawa diagram.
The missing evidence. You recognize it by answers nobody can check: "lack of training," "not enough attention," "it's always been this way."
The fix is the evidence column next to each row: if the evidence does not exist, that answer is a hypothesis, not a link [2].
The three deviations have already appeared row by row in the table: here they get a name.
The final test is a reading one: reread the chain from the bottom up, replacing "why" with "therefore," and if it does not hold, one of the links is an opinion.
Limits and conditions of applicability
The low repeatability of the result is documented: different teams working on the same problem arrive at different causes [2].
The chain counts as an analysis because each answer was verified, not because it was written as a group.
The critical literature on the family [3] comes from the analysis of adverse events in healthcare, where investigations are mandatory and repeated.
The flaws it points out should be read as a methodological risk, not as a measured frequency in Italian companies.
The packaging line case is hypothetical and built for this article: the figures serve to show the procedure, not to estimate a result.
When the chain stops early, the action addresses a symptom and should be declared as such, not passed off as a corrected cause.
FAQ
Why exactly five "whys"?
Five is a rule of thumb, not a constraint: sometimes three steps are enough, sometimes seven are needed [2].
The stopping criterion is not the number but the moment when a further "why" adds no useful information.
Are "5 whys" and "five whys analysis" the same thing?
Yes: it is the same technique, and "5 whys" is the name it goes by in materials of lean origin and in English-language documentation [2].
You will also find "five whys method" and "5 whys analysis," with no difference in procedure.
How long does a session last and who should take part?
Twenty to forty minutes are enough for one chain, preferably on the shop floor rather than in the meeting room: this is a practical recommendation from our editorial team, not a measured figure.
The room needs the people who saw the problem, the people who deal with it downstream and someone with the authority to change the condition that emerges [2].
Is there a 5 whys template in PDF?
The sheet you need is minimal and can be built in a few minutes: one row for each "why," one column for the answer, one column for the evidence that supports it.
At the bottom, two fields are enough: the action with an owner and a date, and the outcome of the check at sixty days.
Practical summary
A 5 whys session starts from a written statement, with a number and a period, agreed on before anyone answers.
In the room are the people who saw the problem, those who deal with it downstream and whoever can change the condition.
Each answer is attached to the answer that generated it, and all plausible answers are followed, not just the first.
Before moving on to the next "why," the answer just given is checked against a document or a number.
The chain stops when a further "why" adds no useful information, and what remains is a condition, not a person.
One rule holds everything together: where the evidence is missing, the row is a hypothesis, not a link.
The last step turns the condition into an action with an owner, a date and an indicator to review later.
Conclusion
The 5 whys are not five questions: they are five verified answers, and the chain stops when it points to a condition the company can change.
The packaging line case reads the same, without changes, in a practice with two team members and in a hundred-employee company, because the sequence of questions does not depend on the industry.
When there are too many plausible answers for a single chain, the step before is the Ishikawa diagram.
When instead you need to understand whether it is worth digging, and with which process, the map is in the guide to business problem solving.
After a few months of verified chains, the discussion in meetings changes subject: no longer who got it wrong last time, but what is missing so that it does not happen again.
The time spent reconstructing what happened becomes available again, and conditions corrected once stop sending you the bill.
Sources and references
[1] Ohno, T., "Toyota Production System: Beyond Large-Scale Production", Productivity Press, Cambridge (MA), 1988 (original Japanese edition 1978). Publisher page: https://www.routledge.com/Toyota-Production-System-Beyond-Large-Scale-Production/Ohno/p/book/9780915299140
[2] Serrat, O., "The Five Whys Technique", Knowledge Solutions no. 30, Asian Development Bank, Manila, February 2009. Available at: https://www.adb.org/publications/five-whys-technique — PDF: https://www.adb.org/sites/default/files/publication/27641/five-whys-technique.pdf
[3] Peerally, M. F., Carr, S., Waring, J., Dixon-Woods, M., "The problem with root cause analysis", BMJ Quality & Safety, vol. 26, no. 5, 2017, pp. 417-422, DOI 10.1136/bmjqs-2016-005511 (open access, PMC5530340). Available at: https://europepmc.org/article/MED/27340202
[4] UNI, "UNI EN ISO 9001:2015+A1:2024 — Sistemi di gestione per la qualità — Requisiti", Ente Italiano di Normazione, in force since October 16, 2024. Available at: https://store.uni.com/uni-en-iso-9001-2015-a1-2024
[5] ISTAT, "Censimento permanente delle imprese 2023: primi risultati", press release, November 14, 2023 (reference year 2022; about 280,000 responding companies, representative of 1,021,618 companies with at least 3 employees). Available at: https://www.istat.it/comunicato-stampa/censimento-permanente-delle-imprese-2023-primi-risultati/ — PDF: https://www.istat.it/it/files/2023/11/REPORTCensimprese.pdf
[6] Accredia, "ISO Survey 2024: le imprese accelerano su sostenibilità e digitalizzazione", AccrediaHub, 2025 (ISO data as of December 31, 2024). Available at: https://www.accredia.it/comunicazione/accrediahub/iso-survey-2024-le-imprese-accelerano-su-sostenibilita-e-digitalizzazione/
[7] Ministero della Salute – Direzione Generale della Programmazione sanitaria, "Metodi di analisi per la gestione del rischio clinico — Root Cause Analysis (RCA), Analisi delle Cause Profonde", Volume I, October 1, 2009 (revised edition December 2010). Available at: https://www.salute.gov.it/new/it/pubblicazione/metodi-di-analisi-la-gestione-del-rischio-clinico-root-cause-analysis-rca-analisi/ — PDF: https://www.salute.gov.it/new/sites/default/files/imported/C_17_pubblicazioni_1103_allegato.pdf