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Samples from: MINITAB Book

Quality and Six Sigma Tools using MINITAB Statistical Software: A complete Guide to Six Sigma DMAIC Tools using MINITAB®

Prof. Amar Sahay, Ph.D.

One of the major objectives of this text is to teach quality, data analysis andstatisticaltoolsusedintheSixSigmaDMAIC(Define,Measure,Analyze,Improve,andControl)process.Thechaptersinthisbookprovideconcepts,understanding,andcomputerapplicationsofSixSigmaDMAICtools.ThestatisticaltoolsusedintheDMAICprocessarediscussedwithstep‐wiseMINITABcomputerapplications.

Thefollowingaresamplesfromthebookrandomlyselectedfromdifferentchapters CHAPTER 1 Introduction to MINITAB Statistical Software: Getting

Started with MINITAB

ChapterHighlights

ThischapterdealswiththedetailsofMINITABstatisticalsoftwareusedwidelyinSixSigma.Aftercompletingthischapter,youwillbecomefamiliarwithMINITABanditsmajorfeatures.Thefollowingtopicsarediscussedinthischapter:

1. IntroductiontoMinitabandgettingstartedwiththesoftware

2. Themain featuresofthesoftware,andhowtoperformdataanalysisusingMinitab

3. Enteringdata,datatypes,dataformats,andanalyzingdata

4. Graphing andeditingdatausing the features suchas:Scale,Labels,DataView,MultipleGraphs,andDataOptionstoeditgraphs

5. ThedescriptiveandstatisticalanalysistoolsforSixSigmausingMinitab

6. SimpletoadvancedanalysistoolsinMinitab

7. AninteractivesessionandatutorialtolearnMinitab

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MINITABStatisticalSoftware:AnOverview 

OUTLINE:CHAPTER1ObjectivesandOverviewMINITABStatisticalSoftware:AnOverviewWorksheet(DataWindow)SessionWindowHistoryWindowAnalyzingYourDataGraphingYourData:Scale,Labels,DataView,MultipleGraphs,DataOptionsPrintingandSavingYourWorkCommandSequenceUsedInThisTextPreparingYourReportChangingdatafromNumerictoTextorTexttoNumericEditingYourGraphsandPlotsAnInteractiveSessionwithMINITAB 

SamplepagesfromChapter1

                                                                                  Mainmenuitems

  

Sessionwindowdisplaystheoutput

Datawindoworworksheet

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Figure2.1:TheSessionandtheDataWindow

 

Figure2.4:DifferentTypesofDatainMINITABWorkSheet

Tutorial  

1.   StartMINITABUsingtheFollowingCommandSequence Start&Programs&MINITAB(ordoubleclickontheMINITABicon)

(Note: the instructions in this chapter are for MINITAB release 16 but mostcommandswillalsoworkwithMINITAB15,thepreviousrelease).

2. EntertheDatainMINITABWorksheetTable2.1showsthenumberofordersreceivedbyacompanyforthepast50weeks.Thisdataisalsoavailable indata file:ORDERS.MTWbutyoumayenterthedataintheMINITABworksheet.Toenterthedatamanually,labelcolumnC1oftheMINITABworksheetwithNo.ofOrdersandenterthe50valuesinthiscolumn.Youmayenterthevaluesinanyorder(roworcolumnwise)butmakesureall50valuesareinone

SuffixDmeanstheColumnisformattedasdates

SuffixTmeanstheColumnisformattedastext

VariableName

ColumnsidentifiedbyC1,C2,..C6.…etc.

NosuffixmeanstheColumnisformattedasnumbers

Therowaboverow1isreservedfornamingvariables

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column (C1). You may enter only part of data if you wish or open the fileORDERS.MTWfromthedatafiles.

          Table2.1NumberofOrdersforthepast50weeks No. of Orders 137 183 133 142 128 164 125 94 163 172 160 170 163 112 138 141 163

 

 

Figure2.9showspartofthedatafileortheworksheet.Oncethedataareentered,usethecommandsequence

File&SaveCurrentWorksheetas

NamethefileORDERSandsaveit.MINITABputsanextension .MTWtoallthedatafiles.

  

Figure2.9:PartoftheDataFileorWorksheetinMINITAB

3.EnteringtheDatainMINITABWorksheet–AnotherExample:::

LabelcolumnC1asshown andenterthe50valuesinthiscolumn

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Figure2.10:EnteringData–EachColumnContainingOneVariable

4.SelectingVariable(s)forAnalysisSelecting a menu item for analysis from the main menu will display a dialog boxshowingthelistofvariables… Stat&GraphicalSummary

willshowthedialogboxshowninfigurebelow.Thevariableorvariablesforanalysisarethenselectedfromthislist.

Refer to figure above. Supposewewant ‘Graphical Summary’ of the variable ‘Strength.’Doubleclickonthisvariablefromthelistofvariablesfromtheleftsideanditwillappearunderthe“Variables”box(seeFigure2.13).Ifyouwantthe‘GraphicalSummary’ofmorethan one variable, highlight all the variables from the variables list using yourmousepointerthenclickthe“Select”buttonatthebottomofthevariableslist.Figure2.14showshowtoselectmorethanonevariableforanalysis.

ColumnsC1toC7 eachcontainsonevariable.

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Figure2.13:SelectingaVariableforAnalysis

Figure2.14:SelectingMultipleVariablesforAnalysis

5.SorttheData  OpentheworksheetORDERS.MTW

Data&SortTocompletetheSortdialogboxthatisdisplayed;doubleclickonC1No.ofOrdersfromtheboxontheleftsideofthedialogboxthatdisplaysthelistofallvariables,thecolumntheyare…..                                                                                   

6.   GeneratePatternedDataintheWorksheet(generatingasequence       ofnumbers) : : Calc&MakePatternedData&SimpleSetofNumbers CompletetheSimpleSetofNumbersdialogboxbytypingthefollowingresponse Fromfirstvalue 1 Tolastvalue 50

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Instepsof 1 Listeachvalue …

Listthewholesequence ….

ClickOKandthenumbers1through50willbestoredincolumnC3oftheworksheet.LabelthiscolumnWeek.

7.   GenerateRandomDataYou can also generate random data from various distributions. For example, togenerate 100 random numbers from a normal distribution, use the followingcommandsequence:

Calc&RandomData&Normal

CompletetheNormalDistributiondialogboxbytypingthefollowingresponse : : :

Click OK and 100 random numbers from normal distribution with mean 50 andstandard deviation 5will be generated and stored in column C4 of theworksheet.NamethiscolumnRandomNumbers.

8.   …..

9.   DoingaSimpleAnalysis….AssumingthedatafileORDERS.MTWisopenwithcolumnC1ofthedatafilewithnumber of orders for 50weeks. To calculate the descriptive statistics for this data,followthecommandsequencebelow

Stat&BasicStatistics&DisplayDescriptiveStatistics

In theDisplayDescriptiveStatisticsdialogbox, typeC1 ordoubleclickC1No.ofOrdersfromthelistofvariablesfromtheleftsidethenclickontheStatisticstab.ThedialogboxinFigure2.16willbedisplayed.

                       

Figure2.16:DescriptiveStatisticsDialogBox

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…..YoumayselectadditionalstatisticsandthenclickOK.YouwillbebacktoDisplayDescriptive Statistics dialog box. Click OK and the selected statistics will becalculatedanddisplayedontheSessionwindowasshowninTable2.2.

        Table2.2

Descriptive Statistics: No. of Orders  

Variable           N   N*    Mean   SE Mean  StDev  Minimum      Q1     Median      Q3 

No. of Orders  50   0  144.52     4.10        29.02    81.00       130.25  142.50   164.75 

Variable         Maximum 

No. of Orders   198.00 

YoucanalsoconstructsimplegraphsofyourdatabyclickingonGraphstabunderDisplayDescriptiveStatisticsdialogbox.Todothegraphs,usethefollowingcommandsequence:

Stat&BasicStatistics&DisplayDescriptiveStatistics

IntheDisplayDescriptiveStatisticsdialogbox,doubleclickonNo.ofOrdersontheleft….

                 

Figure2.17:SelectingStatisticsandGraphs

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10.   ConstructingGraphsusingGraphMenuCommand  YoucanconstructavarietyofgraphsandchartsusingtheGraphcommand.Wehaveexplainedherehowyoucandoastem‐and‐leafplot,ascatterplotandatimeseriesplot.(a) ConstructaStem‐and‐leafplotofNo.ofOrders (stored in columnC1):From

themainmenu,selectthecommandsequence:

Graph& Stem‐and‐leaf

In the Stem‐and‐leaf dialog box, select,C1No. ofOrders or …then clickOK. Thestem‐and‐leafplotshowninFigure2.18willbedisplayed.

Stem‐and‐Leaf Display: No. of Orders  

Stem‐and‐leaf of No. of Orders  N  = 50 Leaf Unit = 1.0 

 2   8   17 

 5   9   046 

 8   10  035 

 9   11  2 

 12  12  558 

 21  13  133446789 

(5)  14  12223 

 24  15  1277 

 20  16  0033333479 

 10  17  002469 

 4   18  38 

 2   19  38 

Figure2.18:Stem‐and‐leafPlot

(b) ConstructaScatterPlot:Selectthecommandsequence

Graph&ScatterplotInthescatterplotsdialogbox,selectSimplethenclickOK.Scatterplot‐simpledialogboxwillbedisplayed. Typeorselect No.ofOrders forYvariablesandWeek for…variables. ClickOK. The scatter plot (shown below) of number of orders for 50weekswillbeshownonthegraphicswindow(Figure2.19).

   

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Figure2.19:ScatterplotofNumberofOrders

(c) ConstructaTimeSeriesPlot

Atimeseriesplotdisplaysdataovertime.Supposewewanttoconstructatimeseriesplotofnumberofordersforthepast50weeks.Selectthecommandsequence

Graph&TimeSeriesPlot

IntheTimeSeriesPlotdialogbox,clickonSimple…… 

 

 

 

 

 

                                                 

                                       

                      Figure2.20:ATime‐SeriesPlotofNumberofOrders11.   SavingYourWork 

BynowyoushouldhavedatainfourcolumnsC1,C2,C3,andC4oftheworksheet.Youcansaveyourworkusing

File&SaveCurrentWorksheetascontinued…

Index

No. o

f O

rder

s

50454035302520151051

200

180

160

140

120

100

80

Time Series Plot of No. of Orders

Week

No. o

f O

rder

s

50403020100

200

180

160

140

120

100

80

Scatterplot of No. of Orders vs Week