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8/9/2019 2. Basic Tools
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Basic Tools of TQM
Seven Basic Tools of Quality is a designation
given to a fixed set of graphical techniques
identified as being most helpful in
troubleshooting issues related to quality.
They are called basic because they are suitable for people
with little formal training in statistics and because they can
be used to solve the vast majority of quality-related issues.
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Basic Tools of TQM
• Scatter Diagram
• Pareto Chart
• Histogram
• Flow Chart
• Cause and Eect Diagram
• Control Charts
• Check Sheet
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Basic Tools of TQM
Check Sheet
generic Tool which can !e used forcollection and anal"sis of data #
structured and $re$ared form that can !eada$ted for wide %ariet" of issuesWhen to se a Check Sheet
&hen collecting data from a $roduction $rocess
&hen collecting data on the fre'uenc" or$atterns of e%ents( $ro!lems( defects( defectlocation( defect causes
When data can be observed and collected repeatedly by the same
person or at the same location
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Basic Tools of TQM
!xample of Check Sheet
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Basic Tools of TQM
"o# to prepare$
Decide what event or problem will be observed – Develop
operational definitions
Decide when data will be collected and for how longDesign the form – Set it up so that data can be recorded simply by
making check (
) marks or Xs or similar symbolsLabel all spaces on the form!est the check sheet for a short trial period to be sure it collects
the appropriate data and is easy to use
"ach time the targeted event or problem occurs# record data on
the check sheet
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Basic Tools of TQM Control Charts
gra$hical techni'ue to stud" the changesto a $rocess o%er time
When to se a Control Chart
When determining whether a process is stable (in statistical control)
When predicting the e$pected range of outcomes from a process
When controlling ongoing processes by finding and correcting
problems as they occur
When determining whether your %uality improvement pro&ect
should aim to prevent specific problems or to make fundamental
changes to the process
When analy'ing patterns of process variation from specialcauses (nonroutine events) or common causes (built into the
process)
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Basic Tools of TQM
!xample of Control Charts
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Basic Tools of TQM
"o# to prepare$hoose the appropriate control chart for your data Determine the appropriate time period for collecting and plotting
data ollect data# construct your chart and analy'e the data
Look for *outofcontrol signals+ on the control chart When one isidentified# mark it on the chart and investigate the cause
Document how you investigated# what you learned# the cause and
how it was correctedontinue to plot data as they are generated – ,s each new data
point is plotted# check for new outofcontrol signalsWhen you start a new control chart# the process may be out of
control -f so# the control limits calculated from the first ./ points
are conditional limits When you have at least ./ se%uential points
from a period when the process is operating in control# recalculate
control limits
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Basic Tools of TQM
%areto Chart
gra$hical techni'ue used to identif" thesigni)cance of indi%idual factors
When to se a %areto chart
When analy'ing broad causes by looking at their specific components
When there are many problems or causes and you want to focus on
the most significant
When analy'ing data about the fre%uency of problems or causes
in a process
When communicating with others about your data
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Basic Tools of TQM
!xample of %areto Chart
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Basic Tools of TQM
"o# to prepare$ Decide what categories you will use to group items Decide what measurement is appropriate ommon measurements are
fre%uency# %uantity# cost and time Decide what period of time the 0areto chart will cover1 2ne work cycle3 2ne
full day3 , week3 ollect the data# recording the category each time (2r assemble data that
already e$ist) Subtotal the measurements for each category Determine the appropriate scale for the measurements you have collected
!he ma$imum value will be the largest subtotal from step 4 5ark the scale
on the left side of the chart onstruct and label bars for each category 0lace the tallest at the far left#
then the ne$t tallest to its right and so on -f there are many categories with
small measurements# they can be grouped as *other+
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Basic Tools of TQM
!xample
Complaint Count
Defect 1 65
Defect 2 109
Defect 3 12
Defect 4 30
Defect 5 789
Defect 6 27
Defect 7 9
Defect 8 621
Defect 9 45
Defect 10 15
Complaint Count Cumulative Count Cumulative &
Defect 5 789 789 45.8
Defect 8 621 1410 81.9
Defect 2 109 1519 88.2
Defect 1 65 1584 92.0
Defect 9 45 1629 94.6
Defect 4 30 1659 96.3
Defect 6 27 1686 97.9
Defect 10 15 1701 98.8
Defect 3 12 1713 99.5Defect 7 9 1722 100.0
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Basic Tools of TQM
!xample
0
100
200
300
400
500
600
700
800
900
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
Defects
Count Cumulati%e *
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Basic Tools of TQM Scatter 'iagram
+sed to identif" the relation !etween%aria!les( !" $lotting $airs of numericaldata( with one %aria!le on each a,isWhen to se a Scatter 'iagram
When trying to determine whether the two variables are related
When your dependent variable may have multiple values for each
value of your independent variable
When you have paired numerical data
o When trying to identify potential root causes of problems
o When determining whether two effects that appear to be
related both occur with the same cause
o When testing for autocorrelation before constructing a control chart
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Basic Tools of TQM
!xample of Scatter 'iagram
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Basic Tools of TQM
"o# to prepare$ ollect pairs of data where a relationship is suspected Draw a graph with the independent variable on the hori'ontal a$is and the
dependent variable on the vertical a$is – 6or each pair of data# put a dot or a
symbol where the $a$is value intersects the ya$is value (-f two dots fall
together# put them side by side# touching# so that you can see both) Look at the pattern of points to see if a relationship is obvious -f the data
clearly form a line or a curve# you may stop !he variables are correlated
7ou may wish to use regression or correlation analysis now
Otherwise, complete the following steps Divide points on the graph into four %uadrants -f there are X points on the
graph#o ount X8. points from top to bottom and draw a hori'ontal lineo ount X8. points from left to right and draw a vertical lineo -f number of points is odd# draw the line through the middle point
ount the points in each %uadrant Do not count points on a line
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Basic Tools of TQM
"o# to prepare$ (contd.)
,dd the diagonally opposite %uadrants 6ind the smaller sum and the total
of points in all %uadrants
, 9 points in upper left : points in lower right; 9 points in upper right : points in lower left
< 9 the smaller of , and ;
= 9 , : ; Look up the limit for = on the trend test table
o -f < is less than the limit# the two variables are relatedo
-f < is greater than or e%ual to the limit# the pattern could have occurredfrom random chance
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Basic Tools of TQM
!xample
N = A + B
= 24
A = 9 + 9 = 18
B = 3 + 3 = 6Q = 6
Limit = 6
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Basic Tools of TQM Scatter 'iagram Considerations
>ere are some e$amples of situations in which you might use a scatter
diagram1 ?ariable , is the temperature of a reaction after @4 minutes ?ariable ;
measures the color of the product 7ou suspect higher temperature
makes the product darker 0lot temperature and color on a scatter
diagram ?ariable , is the number of employees trained on new software# and
variable ; is the number of calls to the computer help line 7ou suspect
that more training reduces the number of calls 0lot number of people
trained versus number of calls !o test for autocorrelation of a measurement being monitored on a
control chart# plot this pair of variables1 ?ariable , is the measurement at
a given time ?ariable ; is the same measurement# but at the previous
time -f the scatter diagram shows correlation# do another diagram where
variable ; is the measurement two times previously Aeep increasing the
separation between the two times until the scatter diagram shows no
correlation
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Basic Tools of TQM
"ven if the scatter diagram shows a relationship# do not assume that one
variable caused the other ;oth may be influenced by a third variable When the data are plotted# the more the diagram resembles a straight line#
the stronger the relationship
-f a line is not clear# statistics (= and
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Basic Tools of TQM
Cause and !ffect 'iagram
+sed to structure the !rain Storming
Session # to sort ideas into usefulcategoriesMan" Possi!le Causes are identi)ed for astated $ro!lem and the eect on the$ro!lem are identi)edWhen to se a Cause and !ffect 'iagram
"specially when a teamBs thinking tends to fall into ruts
When identifying possible causes for a problem
lso called -shikawa or Fish!one Diagram
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Basic Tools of TQM
!xample of Cause and !ffect 'iagram
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Basic Tools of TQM
!xample of Cause and !ffect 'iagram
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Basic Tools of TQM "o# to prepare$
,gree on a problem statement (effect) Write it at the center right of thepaper Draw a bo$ around it and draw a hori'ontal arrow running to it
;rainstorm the ma&or categories of causes of the problem -f this is
difficult use generic headings1o 5ethodso 5achines (e%uipment)o 0eople (manpower)o 5aterialso 5easuremento "nvironment
Write the categories of causes as branches from the main arrow
;rainstorm all the possible causes of the problem ,sk1 *Why does thishappen3+ ,s each idea is given# the facilitator writes it as a branch from
the appropriate category auses can be written in several places if they
relate to several categories ,gain ask *why does this happen3+ about each cause Write sub–causes
branching off the causes ontinue to ask *Why3+ and generate deeper
levels of causes Layers of branches indicate causal relationships
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Basic Tools of TQM *lo# Chart
+sed to identif" the $atterns within thedata collected from multi$le sources and
clu!!ed together # to identif" the meaningof the %ast data !" identif"ing $atternsWhen to se a *lo# Chart
!o study a process for improvement
!o develop understanding of how a process is done
lso called Strati)cation Charts
When better communication is needed between people involved
with the same process
!o communicate to others how a process is done
!o document a process
When planning a pro&ect
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Basic Tools of TQM
!xample of *lo# Chart
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Basic Tools of TQM
"o# to prepare$
Define the process to be diagrammed Write its title at the top of the work
surface Discuss and decide on the boundaries of your process1 Where or when
does the process start3 Where or when does it end3 Discuss and decideon the level of detail to be included in the diagram ;rainstorm the activities that take place Write each on a card or sticky
note Se%uence is not important at this point# although thinking in
se%uence may help people remember all the steps ,rrange the activities in proper se%uence
When all activities are included and everyone agrees that the se%uence iscorrect# draw arrows to show the flow of the process
Ceview the flowchart with others involved in the process (workers#
supervisors# suppliers# customers) to see if they agree that the process is
drawn accurately
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Basic Tools of TQM "istogram
+sed to identif" the fre'uenc" ofoccurrence of a %aria!le in a set of data #looks %er" much like a !ar chartWhen to se a "istogram
When you want to see the shape of the dataBs distribution#
especially when determining whether the output of a process is
distributed appro$imately normally
When the data are numerical
When analy'ing what the output from a supplierBs process looks like
When seeing whether a process change has occurred from onetime period to another
When determining whether the outputs of two or more processes
are different
When you wish to communicate the distribution of data %uickly
and easily to others
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Basic Tools of TQM
!xample of "istogram
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Basic Tools of TQM
"o# to prepare a "istogram
ollect consecutive data points from a process Determine the number of bars and the range of numbers that go into each
bar
Draw $ and ya$es on graph paper 5ark and label the ya$is for countingdata values 5ark and label the $a$is with the data ranges ( values) from the
worksheet Do not allow for spaces between bars ;efore drawing any conclusions from your histogram# satisfy yourself
that the process was operating normally during the time period beingstudied
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Basic Tools of TQM !xample
'ata
83 75
78 83
91 84
87 79
77 90
80 74
77 81
8787
84 71
72 76
77 83
80 90
93 80
96 81
80 87
78 83
72 9087 87
95 93
83 87
90 74
81 91
87 88
93 73
89 73
Data 50
Max Value 96 Min Value 71
Range 25
No of Bar 9
!i"t# 3
Bars Bars coded *requency
70$72 72 3
73$75 75 5
76$78 78 6
79$81 81 8
82$84 84 7
85$87 87 8
88$90 90 6
91$93 93 5
94$96 96 2
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Basic Tools of TQM
!xample
0
1
2
3
4
5
6
7
8
9
Histogram
Fre'uenc"
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Basic Tools of TQM
Typical shapes of "istogram