Statistical tools & concepts (IATF only)
Plain-language summary
Statistical methods are chosen deliberately during planning (APQP/PFMEA stage), included in the control plan — and the people using them actually understand variation, control, capability and over-adjustment.
What the clause is really asking
Determine the appropriate statistical tools during advance quality planning and verify their inclusion in the control plan; ensure basic statistical concepts (variation, control/stability, capability, consequences of over-adjustment) are understood and applied by personnel involved in collecting, analysing and managing statistical data.
What auditors look for
Auditors check the thread: PFMEA/planning shows the tool decision, control plan shows the tool, the operator/technician at the chart can explain what an out-of-control point means and why chasing every point (over-adjustment) makes things worse.
Typical evidence
Planning records showing tool selection; control plans referencing the tools; statistical training records; interview results at the charts.
How to comply — recommendations
Pick your statistical toolbox per characteristic class during APQP and write it into the control plan. Train the floor on the four concepts in plain language — one toolbox talk with a marble-drop demo beats a day of slides.
Common nonconformities
Tools appearing nowhere in planning records; SPC run by people who cannot read their own chart; operators adjusting on every point (over-adjustment institutionalised).
Related clauses
Builds on ISO 9001 9.1.1
In the book
Chapter 9 — Evaluation — Reading Your Own Instruments treats this clause family in full: what it is really asking, what auditors look for, the evidence that satisfies, how to make it work on a real floor, and where companies stumble. This IATF requirement is covered in the Automotive Edition, in the same six blocks as the ISO clause around it.
Resources for this clause
- ArticleWhich control chart should I use?
- ArticleCp vs Cpk vs Ppk: process capability without the confusion
- Toolkit · $29SPC Control Chart ToolkitPick the right tab, fill the yellow cells, and watch control limits and charts calculate live — no SPC maths, no macros, no setup.
- Free downloadCpk CalculatorPaste your measurements, get Cp, Cpk and predicted yield instantly — prove the process is capable.
- Free masterclass · ~18 minControl Charts MasterclassStatistical process control in plain English — common vs special cause, choosing and building the right chart (X̄-R, X̄-S, I-MR, p/np/c/u), reading the signals, and proving capability with Cp/Cpk.
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