2. Basic Tools

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

Documents

2. Basic Tools