What this is
What is a statistical process control chart review?
What is a statistical process control chart review?
It is a periodic audit of an accumulated control chart: whether the control limits are current, whether the chart is actually maintained and read at the point of production, and whether the pattern of signals over the period means the process is in control and capable, rather than merely producing parts inside specification on the day of the review.
Who carries it out?
Quality engineering, not the operator logging the readings. The review is deliberately a different role from the person plotting the chart, because the questions it asks, is this chart still trustworthy, are ones the person closest to daily production is poorly placed to answer about their own work.
How does it differ from the log?
The log is the per-reading record made continuously at the line. The chart review is a separate, periodic instrument that steps back from any one reading to judge the chart as a whole: are the limits valid, is the chart engaged with, and does the accumulated pattern of signals over the period show the process is capable, a question no single log entry can answer.
Scope
When is a statistical process control chart review required?
The review is the periodic, look-back instrument in the statistical process control programme. Using it in place of the per-reading log, or the study that establishes capability from scratch, produces a review with nothing to look back over.
Use this template when
- The stated review interval for the characteristic has been reached
- A trigger event, such as a process change or a run of signals in the log, calls for the review ahead of schedule
- The workspace is being set up and this singleton needs establishing for the characteristic
- A linked record needs this one to exist: the process control log or the yield analysis it feeds
- Management review or a customer audit requires evidence the chart programme is functioning, not just present
Do not use it for
- Statistical Process Control Log, which is the per-reading record this review looks back across, and should not be re-created inside the review itself
- Manufacturing First Article Inspection, which checks the first part off a setup against every specified characteristic before the run continues
- Statistical Process Capability Study, which establishes from scratch whether a process can consistently hold its tolerance, on a stable run of data
- Gage R&R Study, which measures how much of the chart's own variation comes from the measurement system rather than the process
- Anything outside KnowQuality, which belongs in the workspace that owns that process
Compliance mapping
Which ISO 9001 cl.9.1 requirements does this satisfy?
The review sits inside quality management system requirements to monitor and analyse process performance; ISO 7870 supplies the charting method it is auditing, and ISO 9001 and IATF 16949 supply the obligation to demonstrate the process is both controlled and capable.
| Clause | Requirement | Where it lands |
|---|---|---|
| ISO 9001 cl.9.1.1 | Monitoring and measurement of process performance, with methods appropriate to the results needed and results retained as evidence | Chart setup |
| ISO 7870-2 | Control limits derived from the process's own data, recalculated when the process basis for them changes | Chart setup |
| IATF 16949 cl.9.1.1.1 | Statistical concepts, including variation, control and capability, applied and understood at the point of use | Signals |
| ISO 7870-1 | Interpretation of accumulated points against run rules to distinguish special-cause signals from common-cause variation | Signals |
| ISO 9001 cl.10.2 | Reaction to nonconformity and evaluation of the need for action to eliminate the cause, evidenced and followed through | Response to signals |
| ISO 9001 cl.9.1.3 | Analysis and evaluation of process data to assess conformity and the performance of the process | Capability |
| ISO 9001 cl.7.1.5 | Control of monitoring and measurement resources, ensuring the data behind the chart is fit for its purpose | Chart setup |
What it does not cover
- Statistical Process Control Log, which is the continuous, per-reading record made by the operator that this review looks back across rather than replaces.
- Manufacturing First Article Inspection, which is the first-piece check performed before a run starts, not a periodic look at an accumulated chart.
- Statistical Process Capability Study, which establishes capability from a dedicated stable-run study, distinct from the ongoing capability conclusion this review reaches from routine data.
- Gage R&R Study, which quantifies measurement-system variation and should be ruled out before chart signals are attributed to the process.
- Production Part Approval Record, which is the customer-facing approval this review's evidence may feed but does not itself constitute.
Global
Statistical Process Control Chart Review requirements by country
The duty to review, not merely keep, a chart arrives through the quality system a site holds and the audit that tests whether it is real.
21 CFR 820.250 (Quality System Regulation, statistical techniques)
Statistical methods used to accept or control product must be established, with procedures and rationale documented and available to review.
An inspector can ask for evidence the limits and their review are current, not just for the chart, and unrecalculated limits do not satisfy this alone.
ISO 9001 cl.9.1 and cl.9.1.3; IATF 16949 cl.9.1.1.1
Certified organisations must monitor process performance, analyse the data, and apply statistical concepts including control and capability where the process demands it.
A certification auditor treats an unreviewed chart as an open finding regardless of how complete the individual log entries are.
UKAS-accredited certification to ISO 9001
UKAS-accredited bodies audit the same ISO 9001 monitoring and analysis clauses as the international standard, with surveillance visits testing whether the review is a live practice.
A UK site relying on ISO 9001 for customer approval will have this review sampled at surveillance audit; a chart with no review history counts as no chart.
How to complete it
How to complete a statistical process control chart review, step by step
The template prompts for a set of checks. Whether the resulting review is worth anything depends on judgement calls the checklist cannot make on its own.
A chart whose limits were set from the specification, or last recalculated before a known process or tooling change, cannot be trusted regardless of how the points plotted against it look. This has to be settled first, because every later signal is being judged against those limits.
A chart maintained in an office by quality, rather than plotted and read by the operator at the line, is a historical record rather than a working control. The review should treat that difference as a finding in its own right, not a detail.
Overadjustment, correcting the process after every point rather than on a genuine out-of-control signal, actively increases variation. A chart showing frequent small corrections is evidence of a control problem even where no formal signal was ever logged.
A good historical capability index does not certify a process that has since drifted out of control, and a process momentarily in control is not thereby proven capable of holding the tolerance over time. The review should reach both conclusions independently and let either one drive action.
What auditors find
Most common statistical process control chart review findings
The chart itself is usually present and usually complete. The findings concern whether the review actually tested its validity rather than its completeness.
| Finding | Clause | What fixes it |
|---|---|---|
| Control limits confirmed as calculated from specification limits rather than process data, undetected until this review. | ISO 7870-2 | Recalculate limits from a stable run of process data and record the basis and date in the chart setup. |
| Limits never recalculated after a known process change, such as a rebuild or a material change. | ISO 9001 cl.9.1.1 | Trigger limit recalculation from the change record rather than waiting for the next scheduled review. |
| Chart maintained in the office and plotted retrospectively rather than at the line by the operator. | IATF 16949 cl.9.1.1.1 | Move the chart to the point of production and confirm the operator plots and reads it in real time. |
| Routine overadjustment evident from the pattern of the data, with no signal recorded to justify the corrections made. | ISO 9001 cl.9.1.3 | Retrain on the difference between common-cause variation and a genuine signal, and restrict adjustment to a documented reaction plan. |
| Out-of-control signal recorded with a reaction plan marked followed, but the action was recorded well after the signal occurred. | ISO 9001 cl.10.2 | Require the response to be timestamped against the signal, and treat a late entry as a finding regardless of the eventual outcome. |
| Capability index reported with no accompanying judgement of whether the capability is adequate for the tolerance in use. | ISO 9001 cl.9.1.3 | Require the adequacy judgement alongside the index, referencing the specification the process is actually held to. |
Case in point
Case in point: the review that checked the wrong thing
A quality engineer reviewed the chart for a machined bore diameter every quarter, confirming the log had no gaps, the operator had signed each shift, and the last four points sat inside the control limits. Capability had been reported adequate a year earlier and was carried forward without recalculation, since nothing in the log had flagged a problem in the meantime.
An audit ahead of a customer requalification found the control limits had been set before a spindle rebuild eighteen months prior and never recalculated. The rebuild had tightened the process's actual variation considerably, so every point the quarterly reviews had passed as 'in control' was judged against limits describing a machine that no longer existed. The process had, in fact, been running comfortably within a much narrower band the whole time, and the reviews had simply never asked where the limits came from before reading the points against them.
The template
The template, field by field
The form exactly as it installs. Every field, option, score and conditional rule is editable, and the links to other templates come with it.
6 sections
- Reference
- QUA-107
- Archetype
- Review
- Record ID
- SPC-2026-000
- Scoring
- Process capability
- Direction
- High is good
- Singleton
- Yes
- Basis
- ISO 9001 cl.9.1
- Links
- Links Process control, Yield
- Tags
- Manufacturing, SPC
- Sections
- 6
- Fields
- 50
- Follow up fields
- 7
- Repeating sections
- 0
- Links out
- 3
Header
16 fieldsReview ID*
Auto sequence. Format SPC-2026-000.
The record's own ID. Other templates point at this value.
Status*
Drives who this goes to next.
- Planned2 pts
- In progress2 pts
- Complete3 pts
- Deferred0 pts
- Open0 pts
- Closed3 pts
- Overdue0 pts
Date and Time*
Raised By*
Site*
Site ID*
Format SITE-000.
Links to FDN-001 Site ID
Line*
Shift*
Line Lead
Batch Number*
Numeric key joining to your ERP batch record.
Links to External system reference
Product*
Production Date*
In Specification Is Not In Control
A process drifting steadily but still inside tolerance will leave tolerance. Control charts show the drift; inspection results do not.
Characteristic*
Chart Type*
Period Reviewed*
Chart setup
6 fieldsControl Limits From Process Data*
Control limits are calculated from how the process actually behaves. Using the specification limits instead defeats the whole method.
- Yes3 pts
- Specification limits used0 pts
Limits Current*
- Yes3 pts
- Out of date1 pt
- Never recalculated0 pts
Subgroup Size And Frequency Appropriate*
- Yes3 pts
- Marginal1 pt
- No0 pts
Chart Maintained At The Line*
- Yes3 pts
- In the office1 pt
- Not maintained0 pts
Operators Plot And Read It*
A chart plotted by quality in an office is a record. A chart plotted by the operator is a control.
- Yes4 pts
- Plot only2 pts
- Neither0 pts
Data Entry Accurate*
- Yes3 pts
- Some errors1 pt
- Many errors0 pts
Signals
6 fieldsPoints Outside Control Limits*
Runs Above Or Below Centre*
Trends Of Seven Or More*
Cycles Or Patterns Present*
- No3 pts
- Some1 pt
- Clear pattern0 pts
Excessive Variation Within Subgroup*
- No3 pts
- Some1 pt
- Yes0 pts
Process In Statistical Control*
- Yes3 pts
- Marginal1 pt
- No0 pts
Response to signals
6 fieldsOut Of Control Signal In Period*
Repeats the control conclusion so the response steps sit in this section.
- No3 pts
- Yes0 pts
Reaction Plan Exists
- Yes3 pts
- Informal1 pt
- None0 pts
Reaction Plan Followed
- Yes3 pts
- Partly1 pt
- No0 pts
Special Cause Found
- Yes3 pts
- Probable1 pt
- No0 pts
Action Recorded At The Time
- Yes3 pts
- Later1 pt
- No0 pts
Overadjustment Occurring*
Adjusting after every point makes variation worse. Only adjust on a genuine signal.
- No3 pts
- Sometimes1 pt
- Routinely0 pts
Capability
3 fieldsCapability Index
Capability Adequate*
- Yes3 pts
- Marginal1 pt
- No0 pts
Capability Study ID
Links to QUA-108 Study ID
Result
13 fieldsItems Assessed*
Excludes anything marked N/A.
Items Failed*
Score Percent*
Calculated on submission. High is good. N/A items leave the denominator.
Result Band*
- Pass3 pts
- Caution1 pt
- Fail0 pts
Completeness Percent*
How much of the template was actually answered. A high score on a half completed form is not a high score.
Action Required*
Raise the action record, then enter its reference here.
- No2 pts
- Yes0 pts
Priority
- High0 pts
- Medium1 pt
- Low3 pts
CAPA ID
Format CAPA-2026-00000.
Links to FDN-014 CAPA ID
Action Owner
Quality Engineer*
Signature*
Production Manager*
Second Signature*
QUA-107 · record IDs look like SPC-2026-000 · Links Process control, Yield
Open in KnowellaRun it with agents
From a document you fill in to a programme that runs itself
The review is a structured audit. What actually fails is the limit basis nobody rechecked, the chart quietly relocated to an office, and a capability conclusion carried forward past the change that invalidated it.
Holds the review against the characteristic's control plan and change history, and flags a review that is due or a limit basis that predates a known process change.
Cross-checks the review against the log it looks back over, surfacing overadjustment or late responses the review itself did not name.
Links the review to the asset's maintenance and rebuild history, so a limit-basis question can be answered from the equipment record directly.
This template lives in KnowQuality — quality and food safety. HACCP, nonconformance, traceability, laboratory and customer complaints.
Meet KnowQuality→Glossary
Statistical Process Control Chart Review definitions and key terms
- Control limit
- The boundary calculated from a process's own variation, valid only until something changes what the process actually does, at which point it must be recalculated.
- Process capability index
- A measure of how comfortably a process's actual variation fits within its specification, distinct from whether the process is currently in statistical control.
- Overadjustment
- Correcting a process in response to ordinary point-to-point variation rather than a genuine signal, which increases variation rather than reducing it.
- Special cause
- A source of variation outside the process's normal behaviour, as distinct from the common-cause variation the control limits are built around.
- Reaction plan
- The documented response required when a signal appears, as distinct from an informal or improvised correction made without reference to it.
FAQ
Frequently asked questions about statistical process control chart review
Can a process pass every specification check and still fail this review?+
Yes, and this is the review's main purpose. A process can produce inside-specification parts throughout the period while its control chart shows a drift, invalid limits, or routine overadjustment, any of which means the process will eventually leave specification even though nothing has failed yet.
How often should control limits be recalculated?+
Whenever the process basis for them changes: a rebuild, a tooling change, a material change, or any other event that alters how the process actually behaves. A fixed recalculation interval alone will miss a change that happens between scheduled reviews, which is exactly what this review exists to catch.
Where should the chart physically live?+
At the line, plotted and read by the operator. A chart maintained in an office and updated from a batch of data afterward is a record of what already happened, not a control, because the chance to react before more product is made against a shift has already passed.
What is wrong with adjusting the process after every reading?+
It treats ordinary variation as a signal, and correcting a process that has not actually moved adds variation rather than removing it. The review looks for this pattern specifically, because it can be present without ever triggering a formal out-of-control signal.
How is this different from the SPC log?+
The log is the continuous, per-reading record made by the operator at the time. This review is a separate, periodic instrument carried out by quality engineering that looks back across the accumulated log to judge whether the limits are still valid and the process remains capable, a question no single logged reading can answer.
Does a good capability index mean the process is in control?+
No. Capability and control are independent findings. A process can be capable historically and still be currently out of control, in which case it will drift out of the tolerance that made it look capable, and a review that reports only the index without checking control has answered half the question.
Keep going
Related templates and programmes
Industries this is written for
Programmes this belongs to
Used together in Statistical Process Control
Maintenance Calibration Record
Records calibration of maintenance instruments such as torque wrenches, pressure gauges and multimeters
Statistical Process Control Log
Records measurements over time so process variation can be seen and acted on before product fails
Process Capability Study
Measures whether a process can reliably hold its specification, using data from a stable run
Manufacturing First Article Inspection
Inspects the first part or pack off a setup against every specified characteristic before the run continues
Statistical Process Capability Study
Establishes whether a process can consistently hold the tolerance it is asked to hold
Production Part Approval Record
Records the evidence pack that approves a part or product for series production, covering drawings, capability, measurement and samples
More in Manufacturing Quality
Manufacturing First Article Inspection
Inspects the first part or pack off a setup against every specified characteristic before the run continues
Statistical Process Capability Study
Establishes whether a process can consistently hold the tolerance it is asked to hold
Production Part Approval Record
Records the evidence pack that approves a part or product for series production, covering drawings, capability, measurement and samples
Rework Instruction Record
Sets out how a specific batch is to be reworked, what checks apply and who authorised it
Customer Specific Requirement Review
Reviews requirements a customer imposes beyond the standard specification, and whether the site can meet them
Written and reviewed by
Siddarth Singh
Founder & Chief Executive Officer, Knowella
Certified Safety Professional and industrial and systems engineer with more than a decade inside food supply chain, freight and manufacturing operations. This page was written against the current text of the standards it cites, not against secondary summaries of them.
- Certified Safety Professional (CSP), Board of Certified Safety Professionals
- MBA, University of Chicago Booth School of Business
- MS and BS, The Ohio State University, Industrial and Systems Engineering
- Six Sigma Black Belt
Sources and last review. Reviewed 16 August 2026 against:
- ISO 9001:2015 clauses 9.1.1, 9.1.3, 10.2 and 7.1.5
- ISO 7870-1, Control charts — General guidelines
- ISO 7870-2, Control charts — Shewhart control charts
- IATF 16949:2016 clause 9.1.1.1, Statistical concepts
- 21 CFR 820.250, Quality System Regulation, statistical techniques
This page is general guidance, not legal advice. Confirm requirements with your jurisdiction’s regulator.