01 · 14 articles
5 Whys Analysis
Toyota’s iterative questioning method. Drill from surface symptom to verifiable root cause in five (or however many) steps.
The 5xWhys library
Root cause analysis, end to end
Sixty-six in-depth guides, real-world case studies, and free downloadable templates across seven root-cause methods. Built for anyone who needs to find the real cause of a problem — not the first cause that comes to mind: operations and support leads, project managers, clinicians, consultants, quality engineers, Lean / Six Sigma practitioners and SREs.
70in-depth articles
7RCA methods
63free templates
8live analysis tools
Why a library, not a blog
Most “blogs” in the quality and reliability space are disconnected posts chasing keywords. This is not that. Every article here belongs to one of seven collections — each built around a single method — so you can read in sequence, compare methods, and move from theory to a working template in three clicks.
The library is maintained by practitioners who have run RCA inside manufacturing cells, software on-call rotations, hospital operating rooms, and regulated supply chains. Every example includes the working numbers: RPN scores, fishbone categories, Pareto percentages, actual corrective actions. Generic examples get cut.
Browse by method
Each collection contains a pillar guide, worked examples, and a free template.
02 · 6 articles
Fishbone Diagram
Ishikawa’s cause-and-effect mapping. Map the full causal landscape across 6M, 6P, or custom categories before drilling into one branch.
03 · 6 articles
FMEA
Failure Mode and Effects Analysis. Proactive risk assessment scoring every failure mode by Severity × Occurrence × Detection (RPN).
04 · 5 articles
Pareto Analysis
The 80/20 rule applied to quality data. Separate the vital few categories from the trivial many before committing improvement effort.
05 · 9 articles
8D Problem Solving
Ford’s Eight Disciplines — the formal corrective-action methodology required across automotive and aerospace supplier quality. Contain, find root cause, fix, prevent.
06 · 5 articles
A3 Thinking
Toyota’s one-page problem-solving canvas. PDCA in visual form: background, current condition, goal, root cause, countermeasures, plan, and follow-up on a single sheet.
07 · 25 articles
Root Cause Analysis
Cross-cutting RCA methodology: how to compare tools, write a problem statement, run PDCA, build a corrective action plan, and choose the right method.
- Root cause analysis — complete guide
- RCA tools compared (5 methods)
- Free RCA report template (Excel, Word, PDF)
- Pareto vs Fishbone: which first?
- Fishbone vs FMEA: investigate vs prevent
- How to facilitate an RCA workshop
- RCA meeting agenda — 60 and 90 minutes
- PPAP checklist — all 18 elements
- OEE calculation + Excel template
- Fault Tree Analysis guide
- The PDCA cycle
- Corrective action plan (CAPA)
- CAPA process under the FDA QMSR + free form
- Corrective action tracking after the analysis
- 23 best books on RCA & quality
Which method, when?
The methods overlap in purpose but differ sharply in timing, scope, and the kind of problem they handle best. Use this as a decision aid before starting an analysis.
| Method | Type | Best for | Output | Typical time |
|---|---|---|---|---|
| 5 Whys | Reactive | Single-incident depth analysis; small team; human-factor or process errors | Linear causal chain to one verifiable root cause | 30–60 min |
| Fishbone | Reactive | Mapping every possible cause category before narrowing down; brainstorming with a cross-functional team | Branching cause map across 6M / 6P categories | 1–2 hours |
| FMEA | Proactive | Pre-launch design or process risk assessment; regulated industries; catching failures before they happen | Ranked RPN worksheet with action plan | 2–20 hours (workshop) |
| Pareto | Data-driven | Prioritization across many defect categories; deciding where to start when everything feels broken | Sorted chart showing the vital few (typically 20%) | 15–45 min |
| Fault Tree | Proactive | Complex systems with multiple contributing causes; safety-critical domains (aerospace, nuclear, medical devices) | Boolean logic tree with probability calculations | 4–40 hours |
| 8D | Workflow | Customer-facing supplier complaints in automotive / aerospace; when formal corrective-action documentation is required | Eight-discipline report (D1–D8) with containment, root cause, and preventive action | 30–60 days |
Most serious investigations use two methods in sequence — typically Fishbone to map the landscape, then 5 Whys on the most likely branch. See the full RCA tools comparison for detailed trade-offs.
If you only read five articles
The foundational pieces — each one is a long-form, worked-example-heavy guide that stands on its own.
Root Cause Analysis: A Complete GuideThe five-step RCA process, when each method applies, and how to move from evidence to corrective action.
RCA · Pillar Fishbone Diagram: The Complete Ishikawa GuideHistory, 6M and 6P category frameworks, full worked example, and the four most common facilitation mistakes.
Fishbone · Pillar FMEA: The Complete GuideRPN formula, 1–10 rating scales, DFMEA vs PFMEA, seven-step workshop process, and regulatory context (IATF, ISO, FDA).
FMEA · Pillar Pareto Analysis: The Complete GuideThe 80/20 principle in quality, how to build a Pareto chart correctly, and the five decisions it makes obvious.
Pareto · Pillar RCA Tools Compared: 5 Whys, Fishbone, FTA, FMEA & ParetoSide-by-side trade-offs with a decision flowchart: pick the right method in under two minutes.
RCA · Comparison