Overview
SIST ISO 7870-1:2020 - "Control charts - Part 1: General guidelines" - provides the conceptual framework and selection guidance for control charts used in Statistical Process Control (SPC). Rather than prescribing specific statistical procedures, this part outlines the philosophy, terminology, chart types, and planning considerations that underpin effective control-charting across manufacturing, service, and administrative processes. It helps users choose the appropriate part of the ISO 7870 series for their needs.
Key topics and technical scope
ISO 7870-1 covers foundational topics and requirements for designing and applying control charts:
- Definitions & symbols: standard terms (control chart, control limit, Shewhart control chart, variables vs attributes charts) and notations referenced to ISO 3534-1/2.
- Control chart concepts: purposes of control charts (process stability, variability estimation, special-cause detection, pattern recognition, capability indication).
- Types of control charts: overview of Shewhart-related charts, charts for variables and attributes (X̄, median, moving average, p, np, c, u, standardized p), and specialized charts (including charts for autocorrelated data).
- Design considerations: guidance on measurement process evaluation, choice of characteristic, subgroup selection, subgroup size, and sampling frequency to ensure reliable monitoring.
- Applications-oriented categories: charts for process stability, process acceptance, and process adjustment (prediction and online control).
- Risk awareness: discussion of decision risks (false alarms and missed signals) and the role of chart design in managing them.
- Practical presentation: Annex on charting styles and colours to promote consistent, interpretable displays.
Note: ISO 7870-1 does not specify statistical control methods (numerical rules or limit calculations); those methods are detailed in the relevant parts of ISO 7870 (for example, ISO 7870-3 is referenced for acceptance control charts).
Practical applications and intended users
ISO 7870-1 is valuable for professionals implementing or improving SPC and control-chart systems:
- Quality engineers and process engineers designing monitoring systems
- Statisticians and methodologists selecting chart types for variable or attribute data
- Production and operations managers seeking online process indicators
- Suppliers, auditors, and conformity-assessment bodies validating SPC practices
- Continuous improvement and Six Sigma practitioners
Typical applications include monitoring process stability, detecting special causes, assessing process capability relative to specifications, managing online adjustments, and designing sampling schemes.
Related standards
- ISO 7870 series (other parts specify statistical methods and chart-specific procedures, e.g., ISO 7870-3 for acceptance charts)
- ISO 3534-1 and ISO 3534-2 (vocabulary and symbols for statistics)
Keywords: ISO 7870-1, control charts, statistical process control, SPC, Shewhart control chart, process stability, process acceptance, process adjustment, variables control chart, attributes control chart.
