Prepared by
M.Ganesh Murugan9715447621
The QC circle was formally organized in
Japan in 1962 by Japanese Union of
Scientists and Engineers (JUSE) and the man who initiated the idea is Dr.Kaoru
Ishikawa
The organization gets the total man Humanize the work i.e. Quality of work life is
stressed and improved Brings out extra-ordinary qualities from ordinary
people To display the human capabilities fully and
eventually draw out infinite possibilities Prepares the employer and employees to meet
the challenges of the changing time and conditions
Ensure harmony Effective team work Job satisfaction Problem solving capacity Communication Self development Leadership development Safety awareness and housekeeping Productivity Team building Participation Self-discipline
Not just for only quality problems Not a forum for grievances Not a spring-board for demands Not a tool for management to unload problems Not problem-focussed, but performance-
oriented Not for changing the existing organisational
structure or chain of command Not a “cure all” or “sure cure” technique Not a panacea for all ills
One of the prime objectives of QC is to improve the quality of work life and environment
The survival and prosperity of any enterprise depends on the bottom line of the balance sheet i.E. Net profit/economic viability and stability. A higher
level of quality will result in satisfied customer, repeat business, which in turn will improve the profitability, job security and overall harmony of enterprise.
Hence, the emphasis on “quality”
Everybody participates and contributes in the process of decision-making
Problems are chosen, not given Decision by consensus, not by majority Performance-oriented, not problem-oriented Bottom-up approach Management-blessed, not management-directed Members are responsible from the identification
of a problem to implementation of the solution i.E. For total performance
Aims at the quality of work life Does not replace or substitute any of the
systems or structure
Problem identification emanates from The members of the circle Management Staff or technical experts
Several problems are identified and the selection of the problem is the prerogative of the circle
Problem analysis and discuss alternatives Data from specialist, if necessary
Arrive at best solution Circle members discuss various alternatives also
before reaching the best solution
Management presentation The circle makes its recommendations directly to its
in-charge using a powerful communication Review of recommendations and approval by
management Thoroughly in consultation and coordination with
peripheral departments and approves or disapproves Implementation
Approved recommendations are implemented. Recommendations that are not approved are
Communicated to the circle members. It is imperative to explain the reasons to the members of the circle for not approving their recommendations. Communication should be effective in either case
From the familiarity of the members as well as leaders with the operation in which they are involved
In day-to-day work From the proposals or suggestions by clients From the suggestions by the HOD’s From the suggestions or proposals by any
employee in the organisation From the objectives set out in the company’s
annual plan/targetHowever, it is the prerogative of the circle to select
the problem although the suggestions can emanate from various sources
Positive attitude Frank discussions and brainstorming with
everyone participating in a cooperative manner
QC should exercise a systematic approach Confirms the existence of the problem Understands the nature of the problem Identifies the symptoms Finds out the causes Prepares a systematic programs for study Checks those programs with the other members Delegates assignment to members Seeks advice and assistance if required from outside
agencies
Finds out the various possibilities Uses the relevant techniques that are learnt for
problem-solving Prepares a report of its proposal once it arrives at a
solution Evaluates the relevance and practicability of the
solution Recommends the solution Implements the solution
1.Meeting A QC meeting must be the focal point of all activities The meeting time should be such that it is convenient
and acceptable for all members 2.Subject (themes)
The subject chosen should be in consonance with the policies of management
A subject which is familiar and of common concern to all the members of the circle should be handled first
Only work related problem should be chosen A problem whose solution is within the capability of
the members of QC should be selected The subject should be so chosen for the impact of its
solution As a rule, a problem should be selected which can be
solved within reasonable period of time
3.Managing the activities Give opportunities for simple and brief presentation for
those members who are not used to speaking Before others Familiarize all the members with the environment
gradually Utilize every opportunity of praise Suggest better ways of doing things after appreciating
their efforts What is salt to food is humor to effective discussion
without tension. A sense of humor is a necessary ingredient but strict discipline should prevail
Circle members should display their respective role by earmarking their responsibility
Use simple techniques effectively and thoroughly
A problem must be selected and solved only if the members can assure themselves that it will not reoccur
People must be sufficiently motivated even to the point of becoming greedy in getting the most out of activities
4.Education of QC members QC members must make it a habit to study Read text books as many times as possible and make
the best use of them Develop the habit of getting as much data as possible
from as many sources as possible and utilize them to the maximum extent
Knowledge is not sufficient, but the application of knowledge is more important
What is digestion to food is contemplation to knowledge. Hence applying the knowledge that is acquired in solving the problem is key to the success of circle
Apply the techniques in such a simple manner that everyone can understand
5.Key factors for the success of QC activities Make a master plan and divide into elements Study, discuss and solve the problem with the co-
operation of all the members so that their commitment is assured for the implementation
Constantly review the progress and the status of the solution
6.How is a QC program organized? A qc program is an integrated system made up of
several components – The members The leader The facilitator The executive committee
The facilitator takes direction from the executive committee and co-ordinates the activities of the circle meeting and the leader conducts the meeting in such a way that the
members of the circle participate
7.How to ensure longevity of QC activities?
The following essential ingredients are imperative 7.1.To be problem conscious
The leader, who is normally the group head/shift head should understand the role and function of
Leading the sub-ordinates. They should continuously and constantly learn about the technique.
Support from top and middle management is essential to make qc self-motivating
Peripheral departments also must give their blessings for the continued effort of QC activities. Participation by everyone should not only be encouraged but ensured
7.2.To enhance people’s awareness in 3 areas Quality (quality of entire working life) Problem Improvement
People must be quality conscious in order to promote QC activities. Once people become problem conscious, improvement is bound to
follow
7.3.Ensuring voluntary participation People get real satisfaction when they are totally
committed to think and act on their own For the overall prosperity. If one understands why
the activities should be carried out voluntarily, the commitment is bound to follow
7.4.To find pleasure and sense of satisfaction in the QC activities
There are ten kinds of happiness in QC activities Happiness of developing self-confidence Happiness of being recognized for one’s activities Happiness of displaying one’s ability and capability Happiness of acquiring the ability to identify one’s
capability Happiness to develop and enrich one’s potential ability Happiness to be able to recognize one’s potential ability Happiness to understand and co-operate with the
members of the circle Happiness to have friends and affectionate sub-
ordinates
Happiness to belong to a company where the QC activities are encouraged and promoted
Happiness of gaining indirect material reward through the prosperity and growth of the company
7.5.Training Training and re-training from the top management to
the circle member is an indispensable and inevitable
part of ensuring longevity of circles
The members must also be taught value engineering,
job instruction, job method, job relations, creativity
development and leadership qualities
7.6.How often the circle meetings are held? As a rule of the thumb, circle meetings are held once
in a week
However, some companies have introduced
variations It is desirable to reduce the duration and increase the
frequency of the meeting.
Format enclosed
Form
at
en
close
d
The QC circle is program is an integrated system consisting of the following Steering committee
Divisional review committee
Coordinators and facilitators
Circle leader
Circle members
Steering committee This committee comprises of the executive director,
general managers and a member secretary
(nominated by management). This committee sets
goals and objectives for the QCC activities and
establishes operational guidelines
It meets as often as necessary but at least once a
quarter to review the progress. The secretary is
responsible for the overall coordination of QC circle
activity in the company
Divisional review committee This committee comprises of the divisional head,
departmental heads, coordinators and
facilitators(member secretary). It provides active
support to the circles
The committee meets as often as necessary but at
least once a month to review the progress
Coordinators Organizes training programs for members as and
when new circles are formed
Convenes the steering committee meeting regularly
once in two to three months and maintains the
minutes thereof.
Organizes top management presentations regularly
once in two to three months
Centrally registers circles as and when formed and
also maintains records of number of members,
frequency of management representations, etc.
Co-ordinates and evolves a consensus for norms to
asses the performance of different quality circles and
of different divisions
Co-ordinates and ensures availability of common
facilities to all quality circles
Prepares a budget for the functioning of quality
circles and submits the same to the steering
committee for adoption
Facilitators Is responsible for the successful operation of the
quality circles in his area. He has to be a guide,
counselor, teacher and a catalyst
Ensures necessary facilities for quality circles to
operate effectively lends assistance and support to
the leader whenever required and also helps in the
training of members
Is invited to the meetings of the departmental or
steering committees wherein he gives a resume of
the activities of quality circles in his jurisdiction
Circle leader/deputy leader Makes the necessary facilities available, with the help
of facilitators and others, for enabling quality circles
to perform without constraints
Assigns tasks to different member from time to time
to maintain a high degree of individual involvement
and participation
Trains the members in various problem-solving
techniques and other facets of quality circle
operations, and gives them necessary guidance
whenever required, with the help of the facilitator
and others, if necessary
Maintains a high degree of cohesiveness of his team.
He does not act as a boss in quality circle activities
but as a friend and partner so that conflicts are
avoided and group cohesiveness is maintained all the
time
Ensures that every circle member is involved in circle
activity and a high level of enthusiasm and
involvement is maintained
Plans the agenda of meetings carefully and conduct
meetings regularly and effectively
Ensures discipline and decorum during the meetings
Chalks out action plans for a progressive solution of
problems through data collection, interaction and
sets time bound programs for implementation of the
circle’s recommendations
Encourages and evolves consensus decision-making
processes so that win-lose situations are obviated
Ensures that record-notes of meetings and progress
of problems are maintained in two separate registers
regularly and effectively
Interfaces with other levels of management, the
facilitator and different functional agencies to ensure
the effective working of his quality circle
Takes necessary steps continuously in conjunction
with other members, facilitators, executives and the
department head to ensure that his quality circle
maintains a high degree of morale and enthusiasm
continuously and thereby catalyses the quality circle
movement in the organization to grow steadily and
healthily
Organizes presentations to departmental head and
top management at least once in two to three months
Feeds the information relating to the highlights of his
circle activities to the agency concerned for
publication in appropriate newsletters and journals
Circle members Participate actively in the discussions during the
meeting and all other activities of the circle. They
willingly execute specific assignments that may be
given to them as decided in the circle meetings.
Thus they actively assist leader/deputy leader in
effectively and efficiently conducting the circle
activities
Contribute towards building of a cohesive group
through which they try to achieve the highest
standards of performance
Take part in management presentation
Through their personal conduct and enthusiasm, help
in propagating the quality circles concept in other
areas where circles are yet to be launched
Assimilate the inputs given to them during training
and develop in themselves the capability for
systematically identifying analyzing and resolving
problems and also attain leadership qualities
Check sheet
Stratification
Pareto chart
Cause and effect diagram
Histogram
Scatter diagram
Graph and control chart
A scientific approach of solving problems and
making workplace improvements
Helps individuals/teams of diagnose, solve and
prevent problems
Can be used to solve 90% of workplace
problems
Simple yet powerful histogram
Check sheet is a systematic method of
collecting, recording and presenting the relevant
data in a simple manner Helps individuals/teams
of diagnose, solve and prevent problems
Rationale and Benefits To make data gathering simple, systematic, easy and
effective
To arrange and present data in such a way that it can
be understood and used easily
Enables “management by facts” as opposed to
“management by opinion”
Process performance check sheet
Defect item check sheet
Defect location check sheet
Defect cause check sheet
Task conformation check sheet
Establish what information is needed
Establish “operational definition” for the data to
be collected
Determine 5W and 2H of check sheet
Construct the check sheet
Test the check sheet
Use the check sheet
Use the information (remember three rules of
QC)
Why is the data needed?
What type of check sheet should be used?
Where should the data should be collected
from? (Plant/machine/place)
Who has to collect the data?
(Operator/ supervisor/manager)
When will the data be collected?
(Every hour/ at the time of receipt)
How should the data should be measured?
(Instrument/clock)
How much data is essential?
Check sheet should broadly have three types of
information
Title of the check sheet
Source information Name of the project/ problem theme
Location of data collection
Date and/or time
Name of the person recording data
Content information Column with defect/event name
Column to record frequency
Column to record total
Test the check sheet with at least three
different collectors
Check if the operational definition is really
“operational”
Reconfirm that the columns are relevant and
required
Check if the check sheet is easy to record and
use
Make changes based on the feedback
Explain the check sheet to the data collector
Ensure that the data collector understands the
reason for which the data is being collected
Collect data
Standardize its use to assure consistency
Tally mark = 5
Pay particular attention to irregular data and
irregular conditions
Use data from the check sheet for further
analysis
- Pareto chart, histogram, scatter diagram
Ensure that all the data that is recorded is put
to use OR is likely to be put in future
Regularly audit the use and the usefulness of
check sheet
Goals are too vague
No agreed operational definition
Data is not collected on time
Too much time and effort being spent on
recording in the check sheet
Check sheet is too complex
Different people are using different check sheet
for the same issue
Project Name:
Name of Data Recorder:
Location:
Data Collection Dates:
Defect Types/Event Occurrence
Dates
TOTALSunday Monday Tuesday Wednesday Thursday Friday Saturday
Defect 1
Defect 2
Defect 3
Defect 4
Defect 5
Defect 6
Defect 7
Defect 8
Defect 9
Defect 10
TOTAL
check-sheet-histogram.xls
A technique used to divide the data into sub-categories or classification to provide useful insight into the problem
Root word is “strata” which means Group
Division
Sub-class
Levels
Layers
Stratification is an act of dividing the data based on groups, division, sub-class, causes etc.
Data comes from different sources. e.g:
different machines, instruments, cities,
operators etc.
Data sometimes masks real information.
Stratification helps in getting meaningful
information from data.
Divide the data and conquer the information
List all conditions
Collect and stratify data
Interpret the data
List all conditions that may seem to be cause of the
problem
Collect additional data based on classification, if
necessary
Stratify data based on the classification
Calculate average of each classification or plot
appropriate graph
Look for significant differences or abnormalities
in data
Generate a list of possible causes
Un – stratified data
Stratified dataTime 23/2 24/2 25/2
9:00-10:00 15 14 16
10:00-11:00 1 2 0
11:00-12:00 2 0 1
12:00-1:00 1 0 1
1:00-1:30 lunch
1:30-2:30 10 11 12
2:30-3:30 3 1 0
3:30-4:30 0 2 1
4:30-5:30 1 0 1
Pareto chart is a diagram that shows the order
of the largest number of occurrences by item or
by classes, and the cumulative sum total
Vilfredo Pareto (1848-1923), an
Italian economist discovered in
1897 that 80% of a nation’s wealth
was owned by 20% of the
population
Dr. Joseph.M.Juran applied this
principle to quality management
and called it the pareto principle
Pareto principle: 80% of the problems come from
20% of the causes
Distinguishes between vital few and trivial many
Displays relative importance of causes of
problem
Helps the team to focus on those causes that will
have the greatest impact when solved
20%
80%
InputsCausesEffort
OutputsEffectsResults
Select the problem Collect data Sort data & calculate cumulative frequency Draw the axes Construct the bars Draw the cumulative percentage line Title and label the chart Identify vital few from the trivial many and plan
further action
Select the problem for investigation
Decide what data will be necessary and how to
classify them
Determine the method of collecting data and
period of data collection
Design a separate check sheet if necessary
E.g: causes for service complaints of computer
system
136=100%
It is undesirable that “others” represent high
percentage (should be < 10%)
If the cause of a problem can be solved easily,
implement it even if it belongs to trivial many
Wherever possible, compare monetary data
with frequency data
Draw the Pareto chart before and after
improvement
A diagram which represents meaningful
relationship between an effect and its causes
A diagram which shows the relation between a
quality characteristic and the cause factor
Enables a team to identify, explore and
graphically display all the possible causes
related to a problem
A cause and effect diagram is good for seeing
the whole “causal” relationship
Enables identification of root causes and not
symptoms
Dr. Kaoru Ishikawa developed
the first cause and effect
diagram in 1943 while
consulting for Kawasaki steel
works
Dr.Joseph.M.Juran named it as
Ishikawa diagram
Medium Sized Bone
Effect (characteristi
c)
Effect (characteristi
c)
Big Bone
Small Bone
Dispersion Analysis Type.
Process Flow Classification Type.
Cause – Enumeration Type.
Note
Dispersion analysis type and Cause –
Enumeration type differ only in the method of
construction
State the undesirable effect
Identify the main cause groups
Identify causes and sub-causes
Identify potential root causes
Draw the back Bone and draw a line
Such as man, machine, method, material, measurement, tool
ManMan
MethodMethod
MachineMachine
MaterialMaterial
Measurement
Measurement
Environment
Environment
Brainstorm: Ask “why” questions
ManMan
MethodMethod
MachineMachine
MaterialMaterial
Rod bent
Poor handling
No Inspectio
n High Hardness
Measurement
Measurement
Environment
Environment
Runs out of ideas, focus attention to place
ManMan
MethodMethod
MachineMachine
MaterialMaterial
Rod bent
Poor handling
No Inspectio
n High Hardness
Measurement
Measurement
Environment
Environment
State the undesirable effect
Identify the main process flow diagram
Identify the causes and sub – causes at each
stage of the process
Identify the potential root cause(s)
Draw a vertical line state the undesirable effect
Draw a vertical line state the undesirable effect
State the undesirable effect
List all possible causes using brainstorming
Arrange causes and sub – causes showing the
relationship between cause and effect
Identify potential root cause(s)
Identify all the relevant causes (factors) & the
causes most strongly influencing the effect
(characteristic)
Express the effect (characteristic) “negatively”
The linking question between effect and its
cause is “why?”
Make the same number of causes and effect
diagrams as that of effects
It is a type of run chart used for studying the
process performance over time in order to
understand and reduce variation
Dr.Walter.A.Shewart invented the
control chart
He was working in bell labs on a
project to make all telephones alike
Published the book called
“Economic control of quality of
manufactured product” in 1931
Every process is subject to variation
More the variation in the process, more the loss to
the society
Two types of causes affect variation
Common cause (also known as chronic cause, chance
cause)
The cumulative effect of many small and “individually
uncontrollable” causes of variation in a process. Express the
effect (characteristic) “negatively”
Special cause (also known as sporadic or assignable
cause)
One of a few causes of variation that result in a large
variation in the process
Action on variation entirely depends on type of
cause identified
Control chart is used for differentiating between
common causes and special causes of variation
Control charts also helps in determining whether
the
Process is stable
Process is capable
It helps in predicting process performance
Variable data
Data that can be measured
E.g. Weight, height, length, hardness, diameter, angle
Attribute data
Data that can be counted
E.g. Defects, scratches, dent, spatters, blow, holes,
cracks
Y - Axes Variable Data
subgroups
Central line
Control limits
Data Points
Sub groups
Smaller groups of sample data collected over time
Central line
The average of all the sub group averages
Control limits
The outer limits of “Process Variation”
Collect the data
Calculate sub – group average
Calculate overall average
Calculate the range
Compute average of range
Calculate control limit for X and R
Plot the chart
Interpret the chart
Collect and stratify data into sub groups
1 = X1+X2+X3+X4+X5
n
1 = 47+32+44+35+20
5
= 35.6
Where n is the size of the groups
= 35.6+29.2+22.2+39.2
4
= 35.6
Where K is the size of the sub group
= 1+ 2+ 3+ 4
K
= Maximum value – Minimum value
= 47 – 20 = 27
= 1 + 2 + 3 + 4
K = 27 + 18 + 33 + 31
4
Where K is the size of the sub group
Central line =
Upper control limit : UCL = + A2
Lower control limit : LCL = - A2
A2 is the coefficient whose value depends on
the subgroup size
Central line =
Upper control limit : UCL = D4
Lower control limit : LCL = D3
D3 and D4 are the coefficient whose value
depends on the subgroup size
Vertical axis : and R values
Horizontal axis : sub – group number
Draw the central line : and R
Draw the control limits
Plot the and R values and join the points
Write necessary items like name of the process,
product, size of the subgroup, work conditions,
shift, etc.
Random variation and no systematic pattern
No action required (if Cpk > 1.67)
Presence of special cause
Identify root cause and take action
Presence of special cause
Process has shifted
Presence of special cause
Process is deteriorating
Presence of special cause
Periodic Interference in the process
Presence of special cause
Identify root cause and take action
Process capability is a measure of inherent
variability of the process when compared with the
customer requirements
Assess capability of a process to meet customer’s
requirement
Assist in selecting or modifying a process
Assist in selection of machine
To build quality into the product and process
rather than achieving quality by inspection
Establish process variation
process variation = 6σ
σ = .
d2
d2 is a constant based on sub – group size
Refer slide number 124
Capability = Customer Requirement Process variation
Cp = USL –LSL
6 σ
Cp > 1.33; Process is more capable than customer requirement
Cp = 1.0; Process is just capable of meeting customer’s requirement
Cp < 1.0; Process is not capable of meeting customer’s requirement
Cpk = Minimum (USL - ) ; ( - LSL) 3σ 3σ
Cpk = Cp; process is centered with respect to
customer’s requirement
Cpk љ Cp; Process is not centered with respect to
customer’s requirement
Histogram is a type of bar chart representing
the frequency distribution of the data from a
process
Displays large amount of data, that are difficult
to interpret in tabular & graphical form
Shows the relative frequency of occurrence of
the various data values
Provides useful information for understanding
the present performance and predict future
performance of the process
Reveals the centering, variation & shape of the
data
Helps evaluate process capability & the
question “is the process capable of meeting
customers requirements?”
Enables corrective action to keep the process
within specification limits
Excellent planning and forecasting tool
When the data are numerical
When you want to see the shape of the data’s
distribution, especially when determining
whether the output of a process is distributed
approximately normally
When analyzing whether a process can meet
the customer’s requirements
When analyzing what the output from a
supplier’s process looks like
When seeing whether a process change has
occurred from one time period to another
When determining whether the outputs of two
or more processes are different
When you wish to communicate the distribution
of data quickly and easily to others
Decide on the process measure
Gather data
Prepare of frequency table
Calculate range, class intervals, class width and
boundaries
Draw the axes
Draw the bars
Interpret the histogram
Only one parameter can be used for
constructing the histogram
The data should be variable data, i.e., Measured
on a continuous scale (weight, time,
temperature, dimensions, speed, etc.)
Example : weight of a rice bag
For accurate analysis of mean, dispersion and
patterns, collect at least 50 to 100 data points
98.7 100.6 100.2 100.6 100.3 100.3 98.6 99.6
100.0 100.3 99.9 99.9 99.9 100.8 100.5 99.5
100.4 99.7 100.2 99.8 100.1 99.7 100.4 99.8
99.6 100.3 99.4 100.4 99.0 99.9 99.5 99.2
101.5 99.3 101.3 99.2 100.9 100.1 101.6 100.2
100.5 101.1 100.0 101.2 100.1 99.4 99.1 100.1
99.2 100.0 99.6 100.0 100.2 101.4 101.0 100.2
101.0 98.8 100.7 100.3 100.8 100.1 100.0 100.9
Calculate the number of data points, n
Determine the range, R
Determine the number of class intervals, k
Determine the class width, H
Establish the class boundaries
Establish class intervals
Construct the frequency table
Calculate the number of data points, n
Count the number of data points “n” in the sample
n = 64 data points
Calculate the number of data points, n
Determine the range, R
Determine the range “R” in the sample. Range is the
smallest value in the set of data subtracted from the
largest value
R = Xmax – Xmin
R = 101.6 – 98.6 = 3.0
Calculate the number of data points, n
Determine the range, R
Determine the number of class intervals, k
Determine the number of class intervals, “k” needed.
The following table can be used as a thumb rule
No. of data points
No. of classes “k”
< 50 5 – 7
50 – 100 6 – 10
100 – 250 7 – 12
> 250 10 - 20
k = 7 cl
asses
Calculate the number of data points, n
Determine the range, R
Determine the number of class intervals, k
Determine the class width, H
Determine the class width “H”. The formula for this is
H = R/k
This should be rounded off to a suitable value
depending upon the data collected
H = 3.0 / 7
H = 0.428 ~ 0.5
Calculate the number of data points, n
Determine the range, R
Determine the number of class intervals, k
Determine the class width, H
Establish the class boundaries
Use the smallest individual measurement in the
sample or round off to the next appropriate lowest
round number. This will be the lower end point for the
first class interval
Do the same for the highest number. This will be the
higher end point for the last class interval
Class Boundaries – 98.5 & 102.0
Establish class intervals
Add the class width “H” to the lower end point. This
will be the lower end point for the next class interval
Each class interval must be mutually exclusive
Add the class width to the lower class boundary until
the “K” class intervals and/or the range of all the
numbers are obtained
98.50 – 98.99 100.00 – 100.49
99.00 – 99.49 100.50 – 100.99
99.50 – 99.99 101.00 – 101.49
101.50 – 101.99
Construct the frequency table
Process Centering
Process Variation (Dispersion)
Histogram Shape
Process Comparison with specification(Process
Capability)
Process Centering
Process Centering
Process Centering
Process Variation (Dispersion)
Process
too
variable
Process
within
requiremen
ts
What is
the
variation
or spread
of the
data? Is it
too
Variable?
Histogram Shape
Normal distribution
Skewed distribution
Distribution with isolated island
Bi-modal distribution
Process Comparison with specification(Process
Capability)
Process
capable and
centered
Maintain
Process
Process
capable but
not centered
Re-set to
centre the
Process
Process Comparison with specification(Process
Capability)
Process just
capable and
centered
Reduce
variation to
avoid defects
Process just
capable but not
centered
Centre process
and reduce
variations
Process Comparison with specification(Process
Capability)
Process not
capable but
centered
Reduce process
variation to avoid
defects
Choose critical process parameters
Gather as much as data as possible
Choose appropriate class intervals, width,
boundaries and scale
Specify targets and specification limits
Take corrective action and verify
Before drawing any conclusions from your
histogram, satisfy yourself that the process was
operating normally during the time period being
studied. If any unusual events affected the
process during the time period of the
histogram, your analysis of the histogram shape
probably cannot be generalized to all time
periods
Analyze the meaning of your histogram’s shape
A chart used to study and identify the possible
relationship between two variables
To identify the possible relationship between
the changes observed in two variables
To establish the
Existence of correlation
Type of correlation
Strength of the relation
To confirm a hypothesis (assumption) that two
variables are related
Provide both visual and statistical means to test
the strength of a potential relationship
Provide a good follow up to a cause and effect
diagram to find out if there is more than just a
consensus connection between causes and
effects
Cake height and Oven temperature
Weight and Height of a man
Population & Literacy levels in a state
Weight error and Earthing voltage
Nonconformance & Operator experience.
Hardness and carbon content
Inspection mistakes and Illumination levels
Elongation of threads and moisture content
Child’s height and Father’s height
Quality characteristic and the factor affecting it
Weight and Height of a Person
Collect paired data
Choose independent and dependent variable
Draw the axes
Plot the points
Label and title the charts
Interpret the chart
Collect 50 – 100 paired data (X,Y) between
which you want to study the relation, and
construct a data chart
Always choose ‘X’ axis for the cause and ‘Y’ axis
for the effect, when the two variables consists
of a factor and quality characteristics
Oven temperature = independent
Cake height = dependent
Find the respective maximum and minimum
values of the variables
M.Ganesh Murugan9715447621