Control chart

profileEva Chan
Controlchartsslides.ppt

© 2012 International Institute for Learning, Inc.

DS – 624

Quality Management

© 2014 International Institute for Learning, Inc.

7-00-*

IIL-LSSGB

Learning objectives

  • Articulate what is a control chart
  • Describe the elements of a control chart
  • Describe the types of control charts
  • Articulate how to use control charts

Lean Six Sigma Green Belt

Introduction to Control

IIL-LSSGB

7-00-*

Roadmap – Control Phase

Define

Houston, we

have a problem

Measure

How bad is it?

Analyze

Find the

Root Cause

Improve

Fix it- Eliminate

Root Cause

Control

Make it

stay fixed

Control Plan

Control Charts

Project Close Out

Lean Six Sigma Green Belt

Introduction to Control

IIL-LSSGB

This roadmap shows the activities and tools of the Control phase. It is designed to give you a good overview of the main steps in Control.

7-00-*

Monitoring the Process
Review of Control Chart Fundamentals

Lean Six Sigma Green Belt

7_TP-*

Transition Planning

IIL-LSSGB

SPC in Control Phase

In the Control Phase, Control Charts are the primary tool for real-time process monitoring – to drive appropriate corrective action.

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

7_TP-*

Chart1

16 30.4848484848 -2.6767206641 63.6464176338
14 30.4848484848 -2.6767206641 63.6464176338
19 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
32 30.4848484848 -2.6767206641 63.6464176338
36 30.4848484848 -2.6767206641 63.6464176338
48 30.4848484848 -2.6767206641 63.6464176338
24 30.4848484848 -2.6767206641 63.6464176338
17 30.4848484848 -2.6767206641 63.6464176338
18 30.4848484848 -2.6767206641 63.6464176338
28 30.4848484848 -2.6767206641 63.6464176338
22 30.4848484848 -2.6767206641 63.6464176338
33 30.4848484848 -2.6767206641 63.6464176338
71 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
32 30.4848484848 -2.6767206641 63.6464176338
17 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
16 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
36 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
19 30.4848484848 -2.6767206641 63.6464176338
15 30.4848484848 -2.6767206641 63.6464176338
26 30.4848484848 -2.6767206641 63.6464176338
29 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
33 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
26 30.4848484848 -2.6767206641 63.6464176338
88 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
Individuals - Installation Time
Mean CL: 30.48

Sheet1

Day Billing Errors Wk 1 2 3 4 5 FW Cars Visual Defects DPU Installation Time
1 13 1 55 75 65 80 57 1 10 60 6 16
2 9 2 90 95 60 60 85 2 12 75 6.3 14
3 7 3 100 75 75 65 62 3 7 42 6 19
4 12 4 70 110 65 60 100 4 14 77 5.5 25
5 13 5 55 65 95 70 70 5 12 69 5.8 32
6 10 6 75 85 65 65 100 6 12 72 6 36
7 24 7 120 110 65 85 50 7 13 76 5.8 48
8 12 8 65 65 90 90 60 8 10 55 5.5 24
9 13 9 70 85 60 65 75 9 9 51 5.7 17
10 11 10 100 80 65 60 90 10 14 78 5.6 18
11 8 11 13 72 5.5 28
12 8 12 13 77 5.9 22
13 10 13 12 74 6.2 33
14 13 14 10 57 5.7 71
15 11 15 11 62 5.6 45
16 14 16 13 41 3.2 32
17 12 17 11 30 2.7 17
18 10 18 15 45 3 25
19 11 19 15 42 2.8 16
20 9 20 14 40 2.9 25
36
27
27
19
15
26
29
45
33
27
26
88
45

Indiv

SigmaXL Control Charts $M$1 IND 12.46875 30.4848484848 imean Installation Time
Sheet1 1 16 16 -2.6767206641 30.4848484848 63.6464176338 indvmean
33 2 14 2 14 -2.6767206641 30.4848484848 63.6464176338
34 3 19 5 19 -2.6767206641 30.4848484848 63.6464176338
4 25 6 25 -2.6767206641 30.4848484848 63.6464176338
5 32 7 32 -2.6767206641 30.4848484848 63.6464176338
6 36 4 36 -2.6767206641 30.4848484848 63.6464176338
M$34 7 48 12 48 -2.6767206641 30.4848484848 63.6464176338
8 24 24 24 -2.6767206641 30.4848484848 63.6464176338
9 17 7 17 -2.6767206641 30.4848484848 63.6464176338
10 18 1 18 -2.6767206641 30.4848484848 63.6464176338
11 28 10 28 -2.6767206641 30.4848484848 63.6464176338
12 22 6 22 -2.6767206641 30.4848484848 63.6464176338
13 33 11 33 -2.6767206641 30.4848484848 63.6464176338
14 71 38 71 -2.6767206641 30.4848484848 63.6464176338
15 45 26 45 -2.6767206641 30.4848484848 63.6464176338
16 32 13 32 -2.6767206641 30.4848484848 63.6464176338
17 17 15 17 -2.6767206641 30.4848484848 63.6464176338
18 25 8 25 -2.6767206641 30.4848484848 63.6464176338
19 16 9 16 -2.6767206641 30.4848484848 63.6464176338
20 25 9 25 -2.6767206641 30.4848484848 63.6464176338
21 36 11 36 -2.6767206641 30.4848484848 63.6464176338
22 27 9 27 -2.6767206641 30.4848484848 63.6464176338
23 27 0 27 -2.6767206641 30.4848484848 63.6464176338
24 19 8 19 -2.6767206641 30.4848484848 63.6464176338
25 15 4 15 -2.6767206641 30.4848484848 63.6464176338
26 26 11 26 -2.6767206641 30.4848484848 63.6464176338
27 29 3 29 -2.6767206641 30.4848484848 63.6464176338
28 45 16 45 -2.6767206641 30.4848484848 63.6464176338
29 33 12 33 -2.6767206641 30.4848484848 63.6464176338
30 27 6 27 -2.6767206641 30.4848484848 63.6464176338
31 26 1 26 -2.6767206641 30.4848484848 63.6464176338
32 88 62 88 -2.6767206641 30.4848484848 63.6464176338
33 45 43 45 -2.6767206641 30.4848484848 63.6464176338

Indiv

Individuals - Installation Time
Mean CL: 30.48

Control Chart Basics

A picture of a process over time (e.g., Time Series Plot)

With Control Limits that help distinguish between Special Cause variation (abnormal) and Common Cause variation (normal or systemic)

The Control Limits are based on the data, not customer or internal requirements

Control Limits

Special Cause

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

7_TP-*

Chart1

16 30.4848484848 -2.6767206641 63.6464176338
14 30.4848484848 -2.6767206641 63.6464176338
19 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
32 30.4848484848 -2.6767206641 63.6464176338
36 30.4848484848 -2.6767206641 63.6464176338
48 30.4848484848 -2.6767206641 63.6464176338
24 30.4848484848 -2.6767206641 63.6464176338
17 30.4848484848 -2.6767206641 63.6464176338
18 30.4848484848 -2.6767206641 63.6464176338
28 30.4848484848 -2.6767206641 63.6464176338
22 30.4848484848 -2.6767206641 63.6464176338
33 30.4848484848 -2.6767206641 63.6464176338
71 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
32 30.4848484848 -2.6767206641 63.6464176338
17 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
16 30.4848484848 -2.6767206641 63.6464176338
25 30.4848484848 -2.6767206641 63.6464176338
36 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
19 30.4848484848 -2.6767206641 63.6464176338
15 30.4848484848 -2.6767206641 63.6464176338
26 30.4848484848 -2.6767206641 63.6464176338
29 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
33 30.4848484848 -2.6767206641 63.6464176338
27 30.4848484848 -2.6767206641 63.6464176338
26 30.4848484848 -2.6767206641 63.6464176338
88 30.4848484848 -2.6767206641 63.6464176338
45 30.4848484848 -2.6767206641 63.6464176338
Individuals - Installation Time
Mean CL: 30.48

Sheet1

Day Billing Errors Wk 1 2 3 4 5 FW Cars Visual Defects DPU Installation Time
1 13 1 55 75 65 80 57 1 10 60 6 16
2 9 2 90 95 60 60 85 2 12 75 6.3 14
3 7 3 100 75 75 65 62 3 7 42 6 19
4 12 4 70 110 65 60 100 4 14 77 5.5 25
5 13 5 55 65 95 70 70 5 12 69 5.8 32
6 10 6 75 85 65 65 100 6 12 72 6 36
7 24 7 120 110 65 85 50 7 13 76 5.8 48
8 12 8 65 65 90 90 60 8 10 55 5.5 24
9 13 9 70 85 60 65 75 9 9 51 5.7 17
10 11 10 100 80 65 60 90 10 14 78 5.6 18
11 8 11 13 72 5.5 28
12 8 12 13 77 5.9 22
13 10 13 12 74 6.2 33
14 13 14 10 57 5.7 71
15 11 15 11 62 5.6 45
16 14 16 13 41 3.2 32
17 12 17 11 30 2.7 17
18 10 18 15 45 3 25
19 11 19 15 42 2.8 16
20 9 20 14 40 2.9 25
36
27
27
19
15
26
29
45
33
27
26
88
45

Indiv

SigmaXL Control Charts $M$1 IND 12.46875 30.4848484848 imean Installation Time
Sheet1 1 16 16 -2.6767206641 30.4848484848 63.6464176338 indvmean
33 2 14 2 14 -2.6767206641 30.4848484848 63.6464176338
34 3 19 5 19 -2.6767206641 30.4848484848 63.6464176338
4 25 6 25 -2.6767206641 30.4848484848 63.6464176338
5 32 7 32 -2.6767206641 30.4848484848 63.6464176338
6 36 4 36 -2.6767206641 30.4848484848 63.6464176338
M$34 7 48 12 48 -2.6767206641 30.4848484848 63.6464176338
8 24 24 24 -2.6767206641 30.4848484848 63.6464176338
9 17 7 17 -2.6767206641 30.4848484848 63.6464176338
10 18 1 18 -2.6767206641 30.4848484848 63.6464176338
11 28 10 28 -2.6767206641 30.4848484848 63.6464176338
12 22 6 22 -2.6767206641 30.4848484848 63.6464176338
13 33 11 33 -2.6767206641 30.4848484848 63.6464176338
14 71 38 71 -2.6767206641 30.4848484848 63.6464176338
15 45 26 45 -2.6767206641 30.4848484848 63.6464176338
16 32 13 32 -2.6767206641 30.4848484848 63.6464176338
17 17 15 17 -2.6767206641 30.4848484848 63.6464176338
18 25 8 25 -2.6767206641 30.4848484848 63.6464176338
19 16 9 16 -2.6767206641 30.4848484848 63.6464176338
20 25 9 25 -2.6767206641 30.4848484848 63.6464176338
21 36 11 36 -2.6767206641 30.4848484848 63.6464176338
22 27 9 27 -2.6767206641 30.4848484848 63.6464176338
23 27 0 27 -2.6767206641 30.4848484848 63.6464176338
24 19 8 19 -2.6767206641 30.4848484848 63.6464176338
25 15 4 15 -2.6767206641 30.4848484848 63.6464176338
26 26 11 26 -2.6767206641 30.4848484848 63.6464176338
27 29 3 29 -2.6767206641 30.4848484848 63.6464176338
28 45 16 45 -2.6767206641 30.4848484848 63.6464176338
29 33 12 33 -2.6767206641 30.4848484848 63.6464176338
30 27 6 27 -2.6767206641 30.4848484848 63.6464176338
31 26 1 26 -2.6767206641 30.4848484848 63.6464176338
32 88 62 88 -2.6767206641 30.4848484848 63.6464176338
33 45 43 45 -2.6767206641 30.4848484848 63.6464176338

Indiv

Individuals - Installation Time
Mean CL: 30.48

Interpreting Control Charts

Signals of being out-of-control

1 or more points outside control limits

2 out of 3 consecutive points on same side of center line in Zone A or beyond

4 out of 5 consecutive points are on the same side of center line in Zone B or beyond

15 consecutive points in Zone C (above or below mean); i.e., “hugging the average”

8 consecutive points
in Zone B or beyond (on either side
of the center line)

1 or more points outside control limits:

This type of pattern indicates a special cause of variation has occurred. Focus should be on pinpointing what was different in the process at the time the data was generated.

2 out of 3 consecutive points on the same side of centerline in Zone A or beyond:

Could be an early warning signal of a process shift. Depending on whether the shift direction is desirable or not, the team should work to identify what the change was that caused the shift so it can be eliminated or preserved.

4 out of 5 consecutive points on the same side of the center line in Zone B or beyond:

Another early warning signal of a process shift.

Lean Six Sigma Green Belt

Transition Planning

7_TP-*

IIL-LSSGB

Types of Control Charts: Selection Tree

Start

I-MR

P-Chart

Xbar-R

Xbar-S

Chart

Yes

No

Yes

Yes

No

Subgroups

Individuals

Occurrences & non-Occurrences

(Discr. Proportion)

Only occurrences

(Discr. Count)

Continuous

No

Discrete

Type of

Data

Individuals or

subgroups?

Is subgroup

size >or=10?

What is

counted?

Equal

subgroup

sizes?

U Chart

NP-Chart

C Chart

Equal

subgroup

sizes?

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

Use this as a roadmap for selecting your control chart.

7_TP-*

Discrete Data Control Charts

P-Chart

U Chart

NP Chart

C Chart

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

Use this as a roadmap for selecting your control chart.

7_TP-*

Continuous Data Control Charts

I-MR Chart

Xbar-R Chart

Xbar-S

Chart

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

Use this as a roadmap for selecting your control chart.

7_TP-*

Select the appropriate Control Chart

A process team will be tracking the proportion of internal audit reports with incomplete data sent week. The number of reports sent each week is 100.

Start

Yes

Occurrences & non-Occurrences

(Discr. Proportion)

Discrete

Type of

Data

What is

counted?

Equal

subgroup

sizes?

NP Chart

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

7_TP-*

Select the appropriate Control Chart

A process team will be measuring the time required to complete the user acceptance testing of product features. They are taking subgroups of five test cases per day.

Start

Xbar-R

Xbar-S

Chart

No

Subgroups

Continuous

Type of

Data

Individuals or

subgroups?

Is subgroup

size >or=10?

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

7_TP-*

Response Planning

Lean Six Sigma Green Belt

Transition Planning

IIL-LSSGB

7_TP-*

Closed Loop Corrective Action

A point above the UCL is a control rule violation.

What process parameter(s) require response & what should the response be (based on magnitude of the problem or alarm)?

Thickness

17.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

5

10

15

20

25

30

35

Target =10.46

LCL=5.22

UCL=15.70

A “closed loop” plan involves a procedure for documenting discrepancies, defects or out-of-control situations, guidelines for action, and specific response guidelines.

Lean Six Sigma Green Belt

Transition Planning

7_TP-*

IIL-LSSGB

Learning objectives

  • Articulate what is a control chart
  • Describe the elements of a control chart
  • Describe the types of control charts
  • Articulate how to use control charts

Lean Six Sigma Green Belt

Introduction to Control

IIL-LSSGB

7-00-*

© 2012 International Institute for Learning, Inc.

Thank you!

© 2014 International Institute for Learning, Inc.

7-00-*

IIL-LSSGB

Mean CL: 30.48

-2.68

63.65

-7.21

2.79

12.79

22.79

32.79

42.79

52.79

62.79

72.79

82.79

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Individuals - Installation Time