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It is a statistical technique in decisionmaking that is used for selection of a
limited number of tasks that producesignificant overall effect. It uses the Pareto principle - the idea that
by doing 20% of work you can generate80% of the advantage of doing the entire
job. Or in terms of quality improvement, a large
majority of problems (80%) are produced by a fewkey causes (20%).
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Pareto analysis is a formal techniqueuseful where many possible courses of
action are competing for your attention.
Basically, it consists of estimating thebenefit delivered by each action withsubsequent selection of a number of the
most effective actions that deliver thetotal benefit reasonably close to themaximum possible one.
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Write out a list of the changes you could
make. If you have a long list, group it into
related changes.
Then score the items or groups. The scoring
method you use depends on the sort of
problem you are trying to solve.
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For example, if you are trying to improve
profitability, you would score options on the
basis of the profit each group might generate.
If you are trying to improve customer
satisfaction, you might score on the basis of
the number of complaints eliminated by each
change.
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The first change to tackle is the one that has
the highest score. This one will give you the
biggest benefit if you solve it.
The options with the lowest scores will
probably not even be worth bothering with -
solving these problems may cost you more
than the solutions are worth.
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Case StudyImplementation of Pareto
analysis.
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A failing service center
Phones are only answered after manyrings.
Staff seem distracted and underpressure.
Engineers do not appear to be wellorganized. They need second visits tobring extra parts. This means thatcustomers have to take more holiday tobe there a second time.
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They do not know what time they willarrive. This means that customers mayhave to be in all day for an engineerto visit.
Staff members do not always seem toknow what they are doing.
Sometimes when staff members arrive,the customer finds that the problemcould have been solved over the
phone
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Grouping & Scoring the
problems.
Lack of staff training: items 5 and 6: 51complaints
Too few staff: items 1, 2 and 4: 21complaints
Poor organization and preparation: item3: 2 complaints
By doing the Pareto analysis above, the
manager can better see that the vastmajority of problems (69%) can besolved by improving staff skills.
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Once this is done, it may be worthlooking at increasing the number of
staff members.Alternatively, as staff members
become more able to solve problemsover the phone, maybe the need for
new staff members may decline. It looks as if comments on poor
organization and preparation may berare, and could be caused by
problems beyond the manager'scontrol.
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By carrying out a Pareto Analysis, themanager is able to focus on training as an
issue, rather than spreading effort overtraining, taking on new staff members,and possibly installing a new computersystem.
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2. FlowchartsFlow charts are easy-to-understand
diagrams showing how steps in a
process fit together. This makes them useful tools for
communicating how processes work,and for clearly documenting how aparticular job is done.
Furthermore, the act of mapping aprocess out in flow chart format helpsyou clarify your understanding of theprocess, and helps you think aboutwhere the process can be improved.
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A flow chart is used to
Define and analyze processes;
Build a step-by-step picture of the processfor analysis, discussion, or communication;and
Define, standardize or find areas forimprovement in a process
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How to make a flow chart
Most flow charts are made up of threemain types of symbol:
Elongated circles, which signify the start orend of a process;
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Rectangles, which show instructions oractions; and
Diamonds, which show decisions thatmust be made
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Within each symbol, write down what thesymbol represents.
This could be the start or finish of theprocess, the action to be taken, or thedecision to be made.
Symbols are connected one to the other
by arrows, showing the flow of theprocess.
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Points to note
Flow charts are simple diagrams thatmap out a process so that it can easily
be communicated to other people.
To draw a flowchart, brainstorm thetasks and decisions made during aprocess, and write them down inorder.
Then map these out in flow chartformat using appropriate symbols for
the start and end of a process, foractions to be taken and for decisions
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Finally, challenge your flow chart to makesure that its an accurate representation
of the process, and that that it representsthe most efficient way of doing the job
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3. Check sheets
The intent and purpose of collectingdata is to either control the production
process, to see the relationshipbetween cause-and-effect, or for thecontinuous improvement of thoseprocesses that produce any type of
defect or nonconforming product.
A Check Sheet is used for the purposeof collecting data to compile in such away as to be easily used, understoodand analyzed automatically.
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The Check Sheet, as it is beingcompleted, actually becomes a
graphical representation of the data youare collecting, thus you do NOT need anycomputer software, or spreadsheet torecord the data.
It can be simply done with pencil andpaper
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The main functions -
Checks
Production process distribution checks -where the distribution lies.
Defective item checks - to determinewhat kind of defects exist in the process.
Defect location checks - to determinewhere the common defects on a part are
located.
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Defective cause checks - type of defectand thus validate the cause thereof.
Check-up confirmation checks - finalphase of assembly to check the finishedproduct or work.
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4. Histograms
The common person believes that if apart is made in mass production from
a machine, all of the parts will beexactly alike.
The truth is that even with the best of
machines and processes, no two parts are
exactly the same. The product will have a main or "mean"
specification limit, with plus/minus tolerance
that states that as long as the part is
produced within this range, to that range, it is
an acceptable part.
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The object is to hit the targetspecification, however, that is not
always totally possible.
The purpose of a Histogram is to takethe data that is collected from aprocess and then display it graphicallyto view how the distribution of thedata, centers itself around the mean,or main specification.
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The histogram will graphically
show
The center of the data.
The spread of the data.
Any data skewness (slant, bias or run atan angle).
The presence of outliers (product outsidethe specification range).
The presence of multiple modes (orpeaks) within the data.
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5. Scatter diagrams
The Scatter Diagram is another QualityTool that can be used to show the
relationship between "paired data",and can provide more usefulinformation about a productionprocess.
What is meant by "paired data"? The term "cause-and-effect"
relationship between two kinds of datamay also refer to a relationshipbetween one cause and another, orbetween one cause and several
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For example, you could consider therelationship between an ingredient
and the product hardness; betweenthe cutting speed of a blade and thevariations observed in length of parts;or the relationship between theillumination levels on the productionfloor and the mistakes made in qualityinspection of product produced.
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6. Control charts
Control charts are generally used in aproduction or manufacturing environment
and are used to control, monitor andIMPROVE a process.
Common causes are always present andgenerally attributed to machines, material
and time vs. temperature.
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This normally takes a minor adjustmentto the process to make the correction
and return the process to a normaloutput.
However, when making a change to the
process, it should always be a MINOR
change.
If a plot is observed that shows a slightdeviation trend upward or downward,the "tweaking" adjustment should be a
slight change, and then another
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Too often people will over-correct bymaking too big of an adjustment which
then causes the process to dramaticallyshift in the other direction.
For that reason, all changes to theprocess should be SLIGHT and GRADUAL!
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Control Lines
A control chart is a graph or chart withlimit lines, called control lines.
There are basically three kinds of controllines:
the upper control limit (UCL),
the central line (actual nominal size of
product),
the lower control limit (LCL).
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The Xbar & R Control Chart
An Xbar & R Control Chart is onethat shows both the mean value (X ), and the range ( R ).
The Xbar portion of the chart
mainly shows any changes in themean value of the process, whilethe R portion shows any changes
in the dispersion of the process.
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This chart is particularly useful inthat it shows changes in meanvalue and dispersion of the
process at the same time, makingit a very effective method for
checking abnormalities within theprocess; and if charted while inprogress, also points out a problemin the production flow in real time
mode.
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7. Fishbone diagram
Cause & Effect Diagrams
Identifying the Likely Causes of Problems
Also called Fish or Fishbone Diagram andIshikawa Diagrams
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Cause and Effect analysis helps you tothink through causes of a problem
thoroughly. Their major benefit is that they push you to
consider all possible causes of theproblem, rather than just the ones that are
most obvious
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Conclusion.
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