Introduction to Quality Improvement Tools

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yWe are what we repeatedly do. We are what we repeatedly do.

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ARISTOTLEARISTOTLE

Quality Improvement Tools At the end of this learning module the learner

will: Understand how QI tools can support valid

decision making during the Quality improvement process

Describe 6 common QI tools Understand the advantages of each tool

The Deming Cycle

Plan

DoStudy

Act

Quality Tools Pareto Chart

Histogram Process flow diagram Check sheet Scatter diagram Control chart Run Chart Cause and Effect Diagram

Pareto Principle Vilfredo Pareto (1848-1923) Italian economist

20% of the population has 80% of the wealth Juran used the term “vital few, trivial many”.

He noted that 20% of the quality problems caused 80% of the dollar loss.

7 Quality Tools7 Quality Tools

Pareto chart

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Pareto Chart

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Pareto analysis uses an ordered histogram to highlight the major causes of quality problems.

Advantages of a Pareto Diagram Helps a team focus on causes that have

the greatest impact Displays the relative importance of

problems in a simple visual format Helps prevent “shifting the problem” where

the solution removes some causes but worsens others

Histogram

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Histograms are graphical frequency tables that visually capture and display the variation in a set of data.

Advanatages of Histogram Displays large amounts of data that are

difficult to interpret in tabular form Shows centering, variation, and shape Illustrates the underlying distribution of the

data Provides useful information for predicting

future performance Helps to answer the question “Is the

process capable of meeting requirements?

Flowcharts Flowcharts

Graphical description of how work is done. Used to describe processes that are to be

improved.

7 Quality Tools7 Quality Tools

Flow Diagrams

" Draw a flowchart for whatever you do. Until you do, you do not know what you are doing,you just have a job.”

-- Dr. W. Edwards Deming.

FlowchartA flowchart diagrams the steps in a process. Flowcharts help problem solvers better understand the process so they can highlight quality problems.

Flow Diagrams

Flow Diagrams

Advantages of Flowcharts Shows unexpected complexity, problem

areas, redundancy, unnecessary loops, and where simplification may be possible

Compares and contrasts actual versus ideal flow of a process

Allows a team to reach agreement on process steps and identify activities that may impact performance

Serves as a training tool

Process Chart Symbols

Operations

Inspection

Transportation

Delay

Storage

Check Sheet

Creates easy-to-understand data Builds, with each observation, a clearer

picture of the facts Forces agreement o the definition of each

condition or event of interest Makes patterns in the data become

obvious quickly xx xxxxxx x

Check Sheet

COMPONENTS REPLACED BY LABTIME PERIOD: 22 Feb to 27 Feb 1998REPAIR TECHNICIAN: Bob

TV SET MODEL 1013

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Capacitors |||| |||| |||| |||| |||| ||

Resistors ||

Transformers ||||

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A check sheet is a fact-finding tool used to collect data about quality problems.

A typical check sheet tallies the number of defects by previously identified categories. The next step is to graph the defects per category in a histogram.

Cause and Effect Diagram

Enables a team to focus on the content of a problem, not on the history of the problem or differing personal interests of team members

Creates a snapshot of collective knowledge and consensus of a team; builds support for solutions

Focuses the team on causes, not symptoms

Effect

Cause

QualityProblem

Materials

EquipmentPeople

Procedures

Cause and Effect Skeleton or Fishbone

A cause-and-effect diagram, or fishbone diagram, is a chart showing the different categories of problem causes.

Fishbone Diagram

QualityProblem

MachinesMeasurement Human

ProcessEnvironment Materials

Faulty testing equipment

Incorrect specifications

Improper methods

Poor supervision

Lack of concentration

Inadequate training

Out of adjustment

Tooling problems

Old / worn

Defective from vendor

Not to specifications

Material-handling problems

Deficienciesin product design

Ineffective qualitymanagement

Poor process design

Inaccuratetemperature control

Dust and Dirt

Cause and effect diagrams Advantages

making the diagram is educational in itself diagram demonstrates knowledge of problem

solving team diagram results in active searches for causes diagram is a guide for data collection

Show the relationships between a problem and its possible causes.

Developed by Kaoru Ishikawa (1953) Also known as …

Fishbone diagrams Ishikawa diagrams

Advantages of Cause-and-Effect Diagrams

Scatter Diagram

Supplies the data to confirm a hypothesis that two variables are related

Provides both a visual and statistical means to test the strength of a relationship

Provides a good follow-up to cause and effect diagrams

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Scatter Diagram

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Scatter diagrams and tightness of points plotted on the graph gives an indication of the strength of the relationship.

A cluster of points resembling a straight line indicates the strongest correlation between the variables. In this graph, there is a strong positive correlation between x and y.

Run Charts Run Charts (time series plot)

Examine the behavior of a variable over time. Basis for Control Charts

Run Chart

Monitors performance of one or more processes over time to detect trends, shifts, or cycles

Allows a team to compare performance before and after implementation of a solution to measure its impact

Focuses attention on truly vital changes in the process

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Control Chart

Focuses attention on detecting and monitoring process variation over time

Distinguishes special from common causes of variation

Serves as a tool for on-going control Provides a common language for

discussion process performance

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Control Chart

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LCL = 1.99

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Process control involves monitoring a production process and charting the results on a control chart. If any of the points plotted falls outside the control limits, the process is out-of-control.

The Seven QC Tools

1. Flowcharts

2. Check sheets

3. Histograms

4. Cause-and-effect diagrams

5. Pareto diagrams

6. Scatter diagrams

7. Control charts