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Chapter 7 Quality Tools


Title: Chapter 1 Making Economic Decisions Author: ENG Last modified by: leet Created Date: 10/24/2006 6:48:00 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Chapter 7 Quality Tools

Chapter 7 Quality Tools
Which tool is best?
  • Tools can serve as the backbone for virtually any
    type of quality improvement effort (Six Sigma,
    TQM, 8D)
  • Graphical representations of data help us
    understand the true importance of data.
  • There is no single one-size fits all solution.
    Every project and problem is different.

Diagnostic Tools
  • Analytical Tools
  • Cause-Effect (CE) diagram
  • Failure mode-effects Analysis (FMEA)
  • XY matrix
  • Affinity diagram
  • Fault tree analysis (FTA)
  • Graphical Tools
  • Histogram
  • Boxplots
  • Probability distribution plots
  • Main-effects plots
  • Pareto charts
  • Run charts
  • Multi-Vari charts
  • Time-series plots
  • Scatter plots

Diagnostic Tools
  • Other Tools
  • Checksheets
  • Scorecards
  • Graphical Rep. of Process
  • Process flow charts
  • Process mapping
  • Cross-functional mapping
  • Deployment diagram
  • Supplier-input-process-output-customer (SIPOC)
  • Input-process-output (IPO) diagram
  • Force-field analysis

Problem Definition
  • A good problem definition will include quantified
    information about the problem, the magnitude of
    the problem, the baseline, and the gap remaining
    to reach a benchmark or desired state
  • Be Specific
  • Use declarative format
  • Quantify
  • Be factual
  • Example of poor problem definition Reduce
    restorable time for severity 1 telephone banking
    problems, focusing on human errors as root cause
  • Example of good problem definition Reduce
    restorable time from 51 per month for severity 1
    telephone banking problems to 30 or less per
    month by the third quarter of this year,
    resulting in annual savings of 4.5M

Y f (x)
  • The transfer equation of Yf(x) where X x1, x2,
    x3,,xn recognizes that a causal relationship
    exits in any process of action performed.
  • Y is a function of one or many xs where Y is the
    dependent variable and the xs are independent
  • X can equal quality, delivery time, cost of the
    product. Therefore Critical to Satisfaction
    refers to any variable that has significant
    influence on one of more of the determinants of
    customer satisfaction.
  • Pareto principal suggests that 80 of the of the
    total error or variance will be caused by 20 of
    the variables. These are the vital few, while
    the remaining are the trivial many. The key
    is to identify these vital few.

Critical-to (CT) Definitions
  • Critical-to-Satisfaction (CTS) characteristics
    expression of the customers vital needs.
  • Critical-to-Quality (CTQ) characteristics- the
    product, service and/or transactional
    characteristics that significantly influence one
    or more CTS in terms of quality.
  • Critical-to-Delivery (CTD) characteristics-
    in terms of delivery.
  • Critical-to-Cost (CTC) characteristics-
    in terms of cost.
  • Critical-to-Process (CTP) characteristics-
    Process parameters that significantly influence a
    CTQ, CTD, and/or CTC.

The Leverage Principle
  • Not all X variable affect the outcome (Y)
  • In Six Sigma process
  • Identify the variables that exert strong
    influence (Vital Few).
  • Then we must focus on controlling these
    variables. Design of Experiments (DOE) is used
    to achieve this objective.

Y X (x1, x2, x3,,xn )
Dependent Independent
Output Input-process
Effect Cause
Symptom Problem
Monitor Control
The Leverage Principle (Variation Reduction
Strategy ?1 ?2 ?3 ?4 ?5 ?6 Total Red. Efforts ?Total Impr.
Baseline 4 11 3 2 1 1 -- 12.33
Reduce each by 1 3 10 2 1 0 0 6 10.68 13.4
Eliminate all but one 0 11 0 0 0 0 11 11.00 10.8
Reduce the vital one 4 8 3 2 1 1 3 9.75 20.9
What does measurement mean?
  • Concept of measurement seek to compare or
    contrast a physical attribute of something to a
    rational and invariant standard ? performance
  • Seek to quantify such gaps for purposes of
    communications, verification, and analysis.
  • Measure subjective matter (customer satisfaction)
    through surveys, questionnaires
  • Measure physical characteristics, time
    characteristics, defect rates.

How do we know if customers are happy? Goal is to
understand how to better satisfy the customer
  • Survey design considerations
  • Length (not too long)
  • Appearance (simple, not busy)
  • Types of questions (statements of fact or
    measures of performance or importance)
  • Types of question formats
  • Closed-ended (yes/no)
  • Rating scales
  • Open-ended questions / probes
  • Other considerations
  • Focus on one theme
  • Usually best to include a midpoint in rating
    scales (i.e. odd number)
  • Try to solicit feelings toward your competitors.
  • Identify specific target control groups
  • At least 10 of customer base
  • Stratify various customer segments
  • Give prior notice, before delivering survey
  • Personalize the survey and cover letter
  • Address confidentiality
  • Offer an incentive or token of appreciation for
  • Follow up with a friendly collection strategy
  • Develop action plans that are based on results
  • Communicate results to customers
  • Follow up with repeat surveys to monitor changes
    over time

Likert scale
  • A subjective scoring system that allows a person
    being surveyed to quantify likes and preferences
    on a 5-point scale, with 1 being the least
    important, relevant, interesting, or other, and 5
    being most excellent, important, etc
  • Strongly Agree / Agree / Undecided / Disagree /
    Strongly Disagree
  • Very Frequently /Frequently /Occasionally /Rarely
    /Very Rarely /Never
  • Very Important / Important / Moderately Important
    / Of Little Importance / Unimportant
  • Excellent / Above Average / Average / Below
    Average /Extremely Poor
  • Almost Always True / Usually True / Often True /
    Occasionally True / Sometimes But Infrequently
    True / Usually Not True / Almost Never True

Continuous Scales
  • If the data are nonlinear (i.e., with a very wide
    range of values), then a logarithmic scale (in
    this case base 10) may be more appropriate.
  • Linear Scale A scale with equal divisions for
    equal values

Analytical Tool Cause-Effect (CE) Analysis
  • CE diagram (fishbone diagram) uses collective
    knowledge to identify the main causes (x) of the
    effect (y) under study.
  • Manufacturing diagrams (Six Ms measurement,
    manpower, machines, materials, methods, and
    mother nature).
  • Transactional diagrams (4 Ps Policies,
    procedures, personnel, environment).
  • Graphical way to show relationships between
    inputs and outputs.
  • Label each cause with a C (fixed variable), N
    (Noise) or X (experimental independent
  • CE Diagrams can be constructed using MINITAB
    (page 156-157)

Cause-Effect (CE) Analysis
Analytical Tool Failure Mode Effects Analysis
  • Used to assess risks from potential product ,
    service, transaction or process failure modes.
  • Widely used in the Analyze and Improve phase, can
    also be used in Control phase.
  • Helpful to assist in
  • Improving or designing more robust products,
    services processes
  • Designing safer products and processes
  • Designing safer delivery systems
  • Receiving fewer complaints and reducing the
    organizations guarantee costs
  • Creating fewer problems or minimizing them in
    everyday business processes
  • Provide improvement teams with prioritized causes
    and identifying which causes need to be
    eliminated urgently.

How does FMEA work?
  • Focus on Severity, Occurrence and Detectability
    of each process. Then calculate the the Risk
    Priority number (RPN)
  • Each organization can define their own scale
    (1-10, 1-5 )as long as they are consistent
    across the organization.
  • Example of FMEA analysis for Auto manufacturer
  • Start with a grid to define the potential failures

Product or Process Failure Mode Failure Effects SEV Causes OCC Controls DET RPN Actions Plans PS PO PD PRPN
Engine Overheat Engine Damage                        
Battery Doesn't retain charge Car doesn't start                        
Brakes Brake failure Can't STOP car                        
FMEA Severity, Occurrence Detectability
Rating Criteria
1 Is not noticed by anybody, has no effect
2 Is not noticed, has only an insignificant effect
3 Causes only small irritations
4 Modest loss of performance
5 Fall in performance level consequence is customer's complaints
6 Fall in performance level that disturbs the capacity to function
7 Disturbed capacity function that leads to an increase in customer dissatisfaction
8 Product or service becomes useless
9 Product or service is illegal
10 Customer or employee is injured or killed.
Product or Process Failure Mode Failure Effects SEV Causes OCC Controls DET RPN Actions Plans PS PO PD PRPN
Engine Overheat Engine Damage                        
Battery Doesn't retain charge Car doesn't start                        
Brakes Brake failure Can't STOP car                        
FMEA Severity, Occurrence Detectability
Rating Criteria Probability
1 Once every 6-100 yrs lt2/1,000,000,000
2 Once every 3-6 yrs lt3/10,000,000
3 Once every 1-3 yrs lt6/1,000,000
4 Once a year lt6/100,000
5 Once every 6 months lt1/10,000
6 Once every 3 months lt0.33
7 Once a month lt1
8 Once a week lt5
9 Every 3 to 4 days lt30
10 More than once a day gt30
FMEA Severity, Occurrence Detectability
Rating Criteria
1 The cause of the failure is obvious and can be hindered simply
2 All units are to be inspected automatically
3 Statistical process controls with a systematic failure cause test and corresponding Actions
4 Statistical process controls are to be conducted with a systematic failure cause test.
5 Statistical process controls are to be conducted
6 All units are to be inspected manually and avoidance actions installed
7 All units are to be inspected manually
8 Manual inspections are to be conducted frequently
9 Manual inspections are to be conducted occasionally.
10 The defect caused by the failure is not detectable
  • Risk Priority number (RPN) is calculated by
  • Severity x Occurrence x Detectabillity

Analytical Tool XY Matrix
  • XY matrix allows everyone involved with a process
    to agree on output (ys) critical to the survey,
    transaction and/or customer.
  • Matrix allows the team to assign the level of
    importance of each variable (x) to the output
  • EXAMPLE of XY matrix as relates to a coffee
  • If the results/ranking were generated during a
    brainstorm session than they should be verified
    based on actual data.

Graphical Tool Pareto Charts
  • Pareto charts help identify the top factors
    (vital few)
  • Order X in descending order.
  • Add a line showing cumulative of total.
  • Based on this which inputs would you focus on to
    insure customer satisfaction?

Graphical Tool Histogram with Normal Curve
Graphical Tool Histogram with Normal Curve
Minitab Calc Random Data Integer Stat Basic
Statistics Graphical Summary
Graphical Tool Boxplot
  • Minimum
  • Maximum
  • Median
  • First Quartile
  • Third Quartile
  • Minitab
  • Stat
  • Basic Statistics
  • Display Descriptive..
  • Boxplot

Graphical Tool Probability Plot
  • Minitab
  • Graph
  • Probability Plot
  • Single

Graphical Tool Main-Effects Plot
  • Main-effects plot graphically compares the level
    of a process output variable at various states of
    process factors
  • Lines with steeper slopes have larger impact on
    the output compared to those lines with little or
    no slope
  • Used to present result from analysis of variance
  • Use to examine the level means for each factor,
    compare the level means for several factors and
    compare the relative strength of the effects
    across factors

Graphical Tool Main-Effects Plot
  • STAT
  • Main Effect Plot

Input Output
X1 0 60
  1 83
X2 0 72
1 71
X3 0 74
  1 69
Graphical Tool Run Chart
  • A line graph of data points plotted in
    chronological order that helps detect special
    causes of variation
  • Understand process variation
  • Analyze data for patterns
  • Monitor process performance
  • Communicate process performance

Graphical Tool Run Chart
Graphical Tool Time-Series Plot
  • A time series plot is a graph showing a set of
    observations taken at different points in time
    and charted in a time series.
  • Outliers values that do not appear to be
    consistent with the rest of the data
  • Discontinuities a break or gap in a process that
    would normally be continuous
  • Trends a general tendency in movement or
  • Periodicities any recurrence at regular intervals

Graphical Tool Time-Series Plot
Graphical Tool Multi-Vari Charts
  • Show patterns of variation from several possible
    causes on a single chart, or set of charts
  • Obtains a first look at the process stability
    over time. Can be constructed in various ways to
    get the best view.
  • Positional variation within a part or process
  • Cyclical variation between consecutive parts or
    process steps
  • Temporal Time variability

Graphical Tool Multi-Vari Charts
Cus. Size Product Cus. Type Satis.
1 1 2 3.54
2 1 3 3.16
1 2 2 2.42
2 2 2 2.70
1 1 3 3.31
2 1 2 4.12
2 2 1 3.24
2 2 2 4.47
2 1 2 3.83
1 1 1 2.94
Cus. Size 1 small 2 large Product 1
Consumer 2 Manuf. Cus. Type 1 Govt 2
Commercial 3 Education
Graphical Tool Multi-Vari Charts
Minitab Stat Quality Tools Multi Vari Chart
Graphical Tool Scatter Plot
  • Show patterns of variation from several possible
    causes on a single chart, or set of charts
  • Obtains a first look at the process stability
    over time. Can be constructed in various ways to
    get the best view.
  • Positional variation within a part or process
  • Cyclical variation between consecutive parts or
    process steps
  • Temporal Time variability

Graphical Tool Scatter Plot
Graphical Tool Scatter Plot
Graphical Tool Scatter Plot
Graphical Tool Scatter Plot
Graphical Tools for Process Rep. Process
  • Visual representation of the major process steps.
  • Useful to compare as is with should be
  • Determine the limits of the process. Clearly
    define where it begins ends.
  • Determine the steps in the process
  • Put the steps into sequence
  • Draw the flow using standard symbols. Add arrows
    to show flow direction.
  • Verify the flow is complete. Is every feedback
    loop complete?
  • Standard symbols

Graphical Tools for Process Rep. Process
Graphical Tools for Process Rep. Process Mapping
  • Process mapping is a workflow diagram to bring
    forth a clearer understanding of a process or
    series of parallel processes
  • Cross-Functional Mapping
  • As-is vs. To-be

Graphical Tools for Process Rep. Process Mapping
Graphical Tools for Process Rep. SIPOC Diagram
  • Supplier-Input-Process-Output-Customer diagram.
  • A high-level picture of the process that depicts
    how the given process is servicing the customer.
  • Useful to discover customer pain points
  • Identify key Ys an Xs with project team.

Suppliers Inputs Process Outputs Customers
Machine manufacturer Bean supplier Filter supplier Cup supplier Coffee beans Water Filter Cup Brewing machine Insert simple flow-chart here Coffee Espresso Repeat (daily) New
Graphical Tools for Process Rep. SIPOC Diagram
Graphical Tools for Process Rep. IPO Diagram
  • Input-Process-Output diagram is another visual
    rep. of a process activity. Based on the
    transfer equation yf(x)

SOPs Supply Chain
x1Forecast x2Buyer X3 AVL x4BOM x5LT x6Ma
rket Dollar Value
Unforecast demand
Environment AVL
Shipping from Supplier
Noise Variables(N)
Graphical Tools for Process Rep. SIPOC Diagram
Other Tools Force-Field Analysis
  • Force-Field Analysis was developed by Lewin
    (1951) and is widely used to inform
    decision-making, particularly in planning and
    implementing change management programs in
  • It is a powerful method for gaining a
    comprehensive overview of the different forces
    acting on a potential policy issue, and for
    assessing their source and strength.

Force -Field Analysis
Other Tools Matrix Analysis
  • Technique for finding new combinations of
    products or services.
  • List the attributes of the product, service or
  • Draw up a table using these attributes as column
  • Write down as many variations of the attribute as
    possible within these columns.
  • Select one entry from each column. By mixing one
    item from each column, you will create a new
    mixture of components. This is a new product,
    service or strategy.
  • Finally, evaluate and improve that mixture to see
    if you can imagine a profitable market for it.

Other Tools Matrix Analysis
Other Tools Checksheets
  • A check sheet is a structured, prepared form for
    collecting and analyzing data
  • Decide what event or problem will be observed.
    Develop operational definitions.
  • Decide when data will be collected and for how
  • Design the form. Set it up so that data can be
    recorded simply by making check marks or Xs or
    similar symbols and so that data do not have to
    be recopied for analysis.
  • Label all spaces on the form.
  • Test the check sheet for a short trial period to
    be sure it collects the appropriate data and is
    easy to use.
  • Each time the targeted event or problem occurs,
    record data on the check sheet.

Other Tools Checksheets
Other Tools Scorecards
  • A balanced scorecard is a central list of
    numbers, which show each key part of an
    organization's success, such as financials,
    people, operations, suppliers, customers, and
    support systems.
  • The numbers should measure not just important
    outcomes, but also the factors which influence,
    or drive, those outcomes.

Other Tools Scorecards
Other Tools Affinity Diagram
  • The affinity diagram organizes a large number of
    ideas into their natural relationships
  • Record each idea with a marking pen on a separate
    sticky note or card. Randomly spread notes on a
    large work surface so all notes are visible to
  • Look for ideas that seem to be related in some
    way. Place them side by side. Repeat until all
    notes are grouped.
  • Participants can discuss the shape of the chart,
    any surprising patterns, and especially reasons
    for moving controversial notes. When ideas are
    grouped, select a heading for each group.
  • Combine groups into supergroups if appropriate.

Other Tools Affinity Diagram
Affinity Diagram