ISO 7870-2:2023
Control charts — Part 2: Shewhart control charts
This document establishes a guide to the use and understanding of Shewhart control chart approach to the methods for statistical control of a process.
This document is limited to the treatment of statistical process control methods using only Shewhart system of charts. Some supplementary material that is consistent with Shewhart approach, such as the use of warning limits, analysis of trend patterns and process capability is briefly introduced. However, there are several other types of control charts which can be used in different situations.
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
3.1 General presence
3.2 Symbols
3.2.1 For the purposes of this document, the following symbols apply
4 Concepts of Shewhart control charts
4.1 Shewhart control chart
4.2 Control limits
4.3 Process in statistical control
4.4 Action limits
4.5 Warning limits
4.6 Type 1 error
4.7 Type 2 error
4.8 Process not in control
4.9 Phase 1 of statistical process control
4.10 Phase 2 of control charts
5 Types of control charts
5.1 Types of Shewhart control charts
5.2 Control charts where no pre-specified values of process parameters are given
5.3 Control charts with respect to given pre-specified values of process parameters
5.4 Types of variables and attribute control charts
5.4.1 Variables control charts
5.4.2 Attribute control charts
6 Variables control charts
6.1 Usefulness of variables control charts
6.2 Assumption of normality
6.3 Pair of control charts
6.4 Average,  chart and range, R chart or average,  chart and standard deviation, s char
6.5 Control chart for individuals, X, and moving ranges, Rm
6.6 Control charts for medians, 
7 Control procedure and interpretation for variables control charts
7.1 Underlying principle
7.2 Collect preliminary data
7.3 Examine s (or R) chart
7.4 Homogenization for s (or R) chart
7.5 Homogenization for  chart
7.6 Ongoing monitoring of process
8 Unnatural pattern and tests for assignable causes of variation
8.1 Natural pattern
8.2 Unnatural patterns
8.2.1 General
8.2.2 Lack of control in the average chart only
8.2.3 Lack of control in the variation chart only
8.2.4 Lack of control in both average and variation charts
8.2.5 Depiction of unnatural patterns
9 Process control, process capability, and process improvement
9.1 Process control
9.2 Process capability and improvement
10 Attribute control charts
10.1 Attribute data
10.2 Distributions
10.3 Subgroup size
10.4 Control chart for fraction nonconforming (p chart)
11 Preliminary considerations before starting a control chart
11.1 Choice of critical to quality (CTQ) characteristics describing the process to control
11.2 Analysis of the process
11.3 Choice of rational subgroup
11.4 Frequency and size of subgroups
11.5 Preliminary data collection
11.6 Out of control action plan
12 Steps in the construction of control charts
12.1 Typical format of a standard control chart form
12.2 Determine data collection strategy
12.3 Data collection and computation
12.4 Plotting  chart and R chart
13 Caution with Shewhart control charts
13.1 General caution
13.2 Correlated data
13.3 Use of alternative rules to the three-σ rule
Annex A (informative) Illustrative examples
Annex B (informative) Practical notices on the pattern tests for assignable causes of variation
Bibliography
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
3.1 General presence
3.2 Symbols
3.2.1 For the purposes of this document, the following symbols apply
4 Concepts of Shewhart control charts
4.1 Shewhart control chart
4.2 Control limits
4.3 Process in statistical control
4.4 Action limits
4.5 Warning limits
4.6 Type 1 error
4.7 Type 2 error
4.8 Process not in control
4.9 Phase 1 of statistical process control
4.10 Phase 2 of control charts
5 Types of control charts
5.1 Types of Shewhart control charts
5.2 Control charts where no pre-specified values of process parameters are given
5.3 Control charts with respect to given pre-specified values of process parameters
5.4 Types of variables and attribute control charts
5.4.1 Variables control charts
5.4.2 Attribute control charts
6 Variables control charts
6.1 Usefulness of variables control charts
6.2 Assumption of normality
6.3 Pair of control charts
6.4 Average,  chart and range, R chart or average,  chart and standard deviation, s char
6.5 Control chart for individuals, X, and moving ranges, Rm
6.6 Control charts for medians, 
7 Control procedure and interpretation for variables control charts
7.1 Underlying principle
7.2 Collect preliminary data
7.3 Examine s (or R) chart
7.4 Homogenization for s (or R) chart
7.5 Homogenization for  chart
7.6 Ongoing monitoring of process
8 Unnatural pattern and tests for assignable causes of variation
8.1 Natural pattern
8.2 Unnatural patterns
8.2.1 General
8.2.2 Lack of control in the average chart only
8.2.3 Lack of control in the variation chart only
8.2.4 Lack of control in both average and variation charts
8.2.5 Depiction of unnatural patterns
9 Process control, process capability, and process improvement
9.1 Process control
9.2 Process capability and improvement
10 Attribute control charts
10.1 Attribute data
10.2 Distributions
10.3 Subgroup size
10.4 Control chart for fraction nonconforming (p chart)
11 Preliminary considerations before starting a control chart
11.1 Choice of critical to quality (CTQ) characteristics describing the process to control
11.2 Analysis of the process
11.3 Choice of rational subgroup
11.4 Frequency and size of subgroups
11.5 Preliminary data collection
11.6 Out of control action plan
12 Steps in the construction of control charts
12.1 Typical format of a standard control chart form
12.2 Determine data collection strategy
12.3 Data collection and computation
12.4 Plotting  chart and R chart
13 Caution with Shewhart control charts
13.1 General caution
13.2 Correlated data
13.3 Use of alternative rules to the three-σ rule
Annex A (informative) Illustrative examples
Annex B (informative) Practical notices on the pattern tests for assignable causes of variation
Bibliography