Lecture Minitab Part 1

8/17/2019 Lecture Minitab Part 1

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MSO4730 LECTURE MINITAB © Dr AndroullaMichaeloudisMINITAB PART 1 and MODULE REPORT 2013- 2014 Data file: FILMTRIAL.MTW

Introduce the theme of the Module Report. Introduce Minitab. Consider the data file FILMTRIAL.MTW . Distinguish between the numerical and categorical variables. Name the remaining columns. Change the numerical codes of the categorical variables to text

codes. Save the data file on the your USB stick. Perform some statistical analysis for numerical variables. Summarise information on one and two categorical variables; Plot graphs such as histograms, boxplots, pie chart, and multiple bar

chart. Copy and past results and graphs in Microsoft Word.

The second assignment is a module report and will entail a statisticalanalysis using the statistical package Minitab version 16.

The structure of the report is given below:

1. Cover.

2. List of Contents

3. Introduction

4. Methodology

5. Statistic al An alysis.

This should include descriptive statistics; cross-tabulations;graphs (e.g. histogram, pie chart, multiple bar charts, scatter

LECTURE MINITAB

INTRODUCTION TO MINITAB AN D MODUL E REPORT

Objectives ofLecture

[A] STRUCTURE OF THE MODULEREPORT .


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diagram); correlation and regression analysis, and confidenceintervals.

6. Conclusion and recommendation.

The theme of the module report is also described in the modulehandout.

‘Film 2011’ is a large corporation specialising in the entertainment industry.Recently a proposal has been put forward to expand the business by buildingits own chain of cinemas UK wide.

Prior to implementing such a proposal a research has been carried out toassess the performance of three other cinema chains (that is, chains A, B,and C) which have already been established throughout the UK. Chain A,unlike the other two chains employs cinema passes which are valid for either4 or 8 weeks (for promotional purposes).

To carry out this assessment the directors of the ‘Film2011’ corporationcollected information on a random sample of 60 cinemas throughout the UK(England, Scotland and Wales). The directors claim that the average totalmonthly sales of the cinemas is £ 285,000 .

Cinemas were randomly selected from England, Scotland and Wales. Eachcinema is run by one manager.Each cinema manager has completed aquestionnaire and the collected data information includes the columns(variables) given below.

1. Number of cinema. (C1)

2. Cinema Chain. (C2)

1 = Chain A 2 = Chain B 3 = Chain C

3. Regional Location of the cinema. (C3)

1 = England 2 = Scotland 3 = Wales

[B ] THEME OF THE MODUL E REPORT.


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4. Location of the cinema. (C4)

1 = In Town 2 = Out of Town

5. Size of the cinema. (C5)

1 = Small (Less than 400 seats)2 = Medium (400 - 1000 seats)3 = Large (more than 1000 seats)

6. Gender of the Manager. (C6)

1 = Male 2 = Female

7. Monthly Rent (£00s). (C7)

8. Distance of the cinema away from the High Street (miles). (C8)

9. Monthly Advertising Expenditure (£). (C9)

10. Monthly weekend sales (£). (C10)

11. Monthly weekday sales (£). (C11)

Note that incomplete information led to missing values. These arerecorded as * . That is, * represents a missing value in Minitab.

The data is s tored u nder th e f i le name FILMTRIAL.MTW (in Minitabformat).

Since the data file has been stored in MINITAB then the data file namecarries the file extension MTW , which stands for M ini T ab W orksheet . That is,the data file is FILMTRIAL.MTW .

The data file contains 60 rows of inform at ion , where each row representsinform ation on a part icular cinema.

The file contains 11 columns of information (C1, C2, …., C1 1) , whereeach colum n represents a variable such as chain of the cinema, regionallocation of the cinema,distance of the cinema away from the High Street,monthly rent (£00s), monthly advertising expenditure (£),gender of themanager running the cinema, chain of the cinema, size of the cinema, and soon. Each column corresponds to a variable (response to a question in thegiven questionnaire).


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Note that the first column, namely C1, is a list of the cinemas and assuch this does not serve any purpose in the report, and therefore thisshould not be used in the statistical analysis.

The directors of the FILM2011 have employed you as a statistical consultantto carry out the appropriate statistical analysis for satisfying the objectives].

1. How to access Minitab version 16 from the University. After you log in,

Click START to open the Start menu. Select ALL PROGRAMS ►. Select MIDDLESEX SOFTWARE and then choose

MINITAB .

2. MINITAB WINDOWS .

This displays your current worksheet (rows, columns andconstants). Once you retrieve the data file FILM2011.MTW , thiswill occupy the first 60 rows and 11 columns of the worksheet.

Note that a saved Minitab worksheet file has the file extension .MTW (that is, M ini T ab W orksheet).

This displays the output (that is, results). This can also allow you totype Minitab commands but this we will not be doing. All commandswill be accessed from the menu bar. Each menu command opens adialog box, which allows you to make further choices.

[C] MINITAB VERSION 16

DATA WINDOW (or WORK SHEET WINDOW).

SESSION WINDOW.

PROJECT MANA GER WINDOW .


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This is another window, which is open but is minimised. Thisincludes several folders among which are the session and worksheetfolders. Once you save the project ( data andresults ), the fileextension .MPJ (that is, M initab P roJ ect ) will be attached to this file.

Note that this file can only be created and accessed from Minitab.

This window appears each time you create a high-resolution graph.

Note that character graphs are displayed in the Session Window. Youare not required to produce character graphs for this report.

This window can be opened by selecting the HELP command fromthe menu bar.

This window can be opened by selecting the ASSISTANT commandfrom the menu bar.

The data file ‘ FILMTRIAL.MTW’ should be accessed from Moodle.

Save this file on your USB stick. Make sure that you also have a copy ofyour work stored on your C drive on your PC or laptop at home (provided youhave either a PC or a laptop). I t is important that you always have abackup of your w ork.

[D] ACCESSING THE DATA FILE: ‘ FILM2011 .MTW’.

GRAPH WINDOW.

HELP WINDOW.

ASSISTANTWINDOW.


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To open the data file FILMTRIAL.MTW , which has been previously saved onyour usb stick drive.

Open Minitab as it has been stated in Section [C] above.

Click on FILE and choose OPEN WORKSHEET … .

In the LOOK IN box select the usbstick drive. Highlight the file FILMTRIAL.

Note that this file is automatically transferred into the box withthe heading FILE NA ME:

Click OPEN . The following message will appear

[E] OPENING THE DA TA FILE: ‘ FILM2011 .MTW’ IN MINITAB .


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Click OK .

NOTE that the file extension that will be added automatically to asaved Minitab worksheet is .MTW (that is, M ini T ab W orks heet ). Thisfile can only be accessed from Minitab.

To check the data information you can click on the Project Manager, whichyou can access as follows:

Either click on the icon on the toolbar which looks like an openbook

[F] TO CHECK THE DATA INFORMATION


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Or click on WINDOW and select PROJECT MANAGER .

Click on COLUMNS and this will allow you to see theinformation on the columns in the worksheet.

NOTE for illustrating the use of Minitab a data file called

FILMTRIAL will be used.

1


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Note that you can clos e the Project Manager by cl ick ingthe top left hand cor ner and s electing NEXT.

The cell below the column label (Cno.) and above row 1 , is reserved for theco lumn name . Give an appropriate name to each column in the worksheet.

Note that only two columns have been left without a name, namely C5 and C6 . The maximum length of 32 characters is allowed for a name.

C5 C6SIZE GENDER

[G] NAMING THE COLUMNS.


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Incomplete information leads to what we call ‘ missing values’ . Inthis dataset missing values were recorded as – 1. Prior to anystatistical analysis it is necessary to replace these missing values by

* since Minitab can only recognise missing values by *. This isalready been done in the datafile FILMTRIAL.MTW. Failure toreplace these missing values will result in inaccurate results in thestatistical analysis.

Note that for making life easy these have already been replacedby * so therefore you will need not have to change the -1 to *.

Looking at the information on columns (see Project Manager) you willsee that Minitab has already identified the columns in which missingvalues are found as well as the number of missing values in eachcolumn.

Note tha t you can f ind out which columns have miss ing va lues bychecking th e column info rmation (fol low the steps of sect ion [F]above).

The categories of each categorical variable are coded using numericalvalues.

For example, the categorical variable REGION (C3) has three categoriesnamely ENGLAND , SCOTLAND and WALES , which are coded using thenumerical codes 1, 2and 3 respectively. That is:

1= England 2= Scotland 3 = Wales

[ H] MISSING VAL UES.

[I] CHANGING THE NUMERICAL CODES OF THE CATEGORICAL

VARIA BL ES TO TEXT CODES.

What are miss ing values?


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Note that 1, 2 and 3 are just labels (or identifiers) used to identify eachcategory. We could have easily used any other numbers for example, 10 =Eng land, 20 = Scotl and and 30= Wales .

This coding helps one to avoid making mistakes while typing in the data andany mistakes you might make will be more easily detected by this coding.For example, typing 11 instead of 1.

To ease the statistical analysis and improve presentation, we would convertthe numerical codes of all categorical variables to text codes.

This is illustrated using the categorical variable REGION (C3).

Click on DATA and choose CODE .

Select NUMERIC TO TEXT… .

Highlight the categorical variable (say e.g. C3) and then click onSELECT . Alternatively, highlight the categorical variable and doubleclick it.

HOW DO WE DO THIS?

1

2

3


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Note that this column now has moved into the box with the headingCODE DATA FROM COLUMNS:

Click inside the box with the heading STORE CODED DATA IN

COLUMNS: . Highlight the categorical variable (e.g. C3) and double click it.

Note we choose the same column if we want the result to be placed backinto the same column. You are advised to do this. This is what we would bedoing here.

Click in the first box under ORIGINAL VALUES , type thenumerical code (in this example, 1) and in the corresponding boxunder NEW type the corresponding text code (in this example,

ENGLAND ).In the second box under ORIGINAL VALUES type the numericalcode, (in this example, 2) and in the corresponding box under NEW type the corresponding text code (in this example, SCOTLAND ).

In the third box under ORIGINAL VALUES type the numerical code(in this example, 3) and in the corresponding box under NEW typethe corresponding text code (in this example, WALES ).

Click OK .

NOTE that


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Distance is a numerical (continuous) variable and represents the distance ofa cinema away from the High Street. We can summarise the information ondistance by using the above command as follows:

Click on STAT and choose BASIC STATISTICS .

Select DISPLAY DESCRIPTIVE STATISTICS… .

Click inside the box with the heading VARIABLES: . Thenumerical variables will now appear in the List box.

Highlight the variable DISTANCE (that is, C8 ) and double clickit.

Click OK .

NOTEYou can also produce a graphical representation of the data (that is, ahistogram or a boxplot or a dotplot or a graphical summary). If you wish todo this then you need to click on GRAPHS and choose the graph of yourchoice. Then click OK and then OK again for executing the command.

EXAMPLE 1


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OUTPUT

Descriptive Statistics: DISTANCE

Variable N N* Mean SE Mean StDev Minimum Q1DISTANCE 59 1 2.651 0.197 1.514 0.500 1.250

Median Q3 Maximum2.750 4.000 6.000

The output now appears in the session window.

Note that the output can be highlighted, copied ( by right clicking the mouseand selecting COPY ) and pasted in a Microsoft word file. The outputhowever needs to be edited.

Note that the output provides you with the SE Mean . This is what we call theStandard Error o f the Mean .

This is something that we havecome not across yet in this module, thereforeyou are asked prior to clicking OK for executing the above command,you click on STATISTICS… .

Remove the option for the SE of Mean by clicking inside the SE ofMean box


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Click on OK

Click on OK to execute the command.

The output now will exclude the SE of Mean whic h is not required inthis cour se.

Note that

N represents the number of observations .N* represents the number of missing values .Mean represents the mean value.Median represents the median value.StDev represents the standard deviation .Minimum represents the minimum value in the data.Maximum represents the maximum value in the data.Q1 represents the first (or lower quartile ) of the data.Q3 represents the third (or upper quartile ) of the data.

OUTPUT

Descriptive Statistics: DISTANCE

Variable N N* Mean StDev Minimum Q1DISTANCE 59 1 2.651 1.514 0.500 1.250

Median Q3 Maximum2.750 4.000 6.000

[Note that the above outp ut has b een edited].

Interpretation.

One manager failed to provide information regarding the distance of thecinema away from the High Street. The distance varies with a minimum ofhalf a mile (0.5 miles) and a maximum of 6 miles. On average we wouldexpect a cinema to be about 2.7 miles away from the High Street with anaverage variation of about 1.5 miles. Seventy-five percent of the cinemashave a distance of 4 miles or less while 25% of the cinemas have a distanceof 1.25 miles or less away from the High Street. The middle 50% of thecinemas have a distance of between 1.25 and 4 miles away from the HighStreet. We also note that the median is slightly higher than the mean value


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indicating a slightly negatively skewed distribution.

Note

that the coefficient of skewness can be obtained by clicking theSKEWNESS box in the STATISTICS … dialoq (see page 1 5 above).

There are two methods that you may use to plot a histogram. A histogramis used to display graphically the distribution of a continuous variable.

When you use the following command (see above)

you are given the chance to plot a histogram by clicking on the

subcommand.

This leads to a further dialog box (see below):

PLOTTING AHISTOGRAM.

STAT BA SIC STATISTICS

DISPLAY DESCRIPTIVESTATISTICS …

GRAPHS …

METHOD 1


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Click the box on the left of HISTOGRAM OF DATA (or HISTOGRAMOF DATA, WITH NORMAL CURVE ).

Click OK .

Click OK .

OUTPUT


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6.04.83.62.41.2

10

8

6

4

2

0

DISTANCE

F r e q u e n c y

Histogram of DISTANCE

Note

You can edit the x-axis label, y-axis label and also make changes tothe title. You can easily do this by double clicking on the x-axis label,y-axis label and title respectively.

Your work will be assessed for presentation and structure and assuch it is necessary to edit the axes and add a clear title to yourgraph. The FREQUENCY should be replaced by the appropriatename. In this case, this is ‘Number of Cinemas ’ .

You can add your initials or any other information you would like atthe foot of the graph by right clicking the mouse, selecting A DD andthen choosing FOOTNOTE. In a similar manner you can add a

T ITLE, … to your graph.

You can edit the bars of the histogram (change the fill pattern and thecolour if you are using a colour printer) by double clicking on the bars.

1. Under the FILL PATTERN , click the button CUSTOM .

2. Choose the TYPE and BA CKGROUND COLOR of your choicehaving in mind that presentation is important. Make sure you


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familiarize yourself with the type of editing a graph (lecture, labsession and in your own free time).

3. Do not use capital letters when naming the axes and giving a title.

After editing the graph, the final version of the graph is:

6.04.83.62.41.2

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Distance of the cinema away from the High Street (miles)

N u m

b e r o

f C i n e m a s

3

0

4

9

5

9

4

9

10

6

Histogram displaying the distance distribution.

NOTE that you c an save a graph if yo u so wish (see sect ion [M]).

Exercise 1. Try plotting a histogram using this approach.

METHOD 2


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The second method for plotting a histogram is carried out by using thefollowing steps:

Click on GRAPH and select HISTOGRAM … .

After selecting the HISTOGRAM … option, the following dialog box appears:

GRAPH HISTOGRAM…

1

2


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Click OK .

Highlight the variable of interest (in this case, DISTANCE) and doubleclick it.

To add a TITLE and a FOOTNOTE (as requested), click on LABELS… .


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Once you add the title and footnote, then click OK . You can now click on DATA OPTIONS… .

From the next dialog box, click on GROUP OPTIONS .


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From the following next dialog box, remove the tick (by clickinginside the box) next to INCLUDE MISSING AS A GROUP .

After doing this, then click OK .

Click OK to produce the histogram.


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6543210

25

20

15

10

5

0

DISTANCE

F r e q u e n c y

Histogram displaying the Distance distribution.

AM

NOTE

The graph needs to be edited as we have explained before. Forexample, the name of the vertical axis is FREQUENCY . It is importantthat this is replaced by the appropriate name, which in this case is‘Number of Cinemas ’ .

The name of the horizontal axis also needs to be replaced by theappropriate name namely ‘Distance of a Cinema away from the HighStreet (miles)’ .

You can also further edit your graph as we have described during thelecture as well as above. Name for the axes should not be in capitalletters. Presentation is very important.

OUTPUT


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6.04.83.62.41.2

10

8

6

4

2

0

Distance of a cinema away from the High Street (miles)

N u m

b e r o

f C i n e m a s

3

0

4

9

5

9

4

9

10

6

Histogram displaying the Distance distribution.

AM

To save the data file on the appropriate drive(or USB drive).

Click on FILE and choose SAVE CURRENT WORKSHEET AS … .

In the SAVE IN select the USB stick drive).

In the FILE NAME enter the file name FILMTRIAL or anyother name you prefer to use for your data file.

You are advised to keep the file name FILMTRIAL.

Click SAVE .

[K ] SAVING THE DA TA (THAT IS, SA VING THE WORK SHEET).

FILE SAVE CURRENT WORKSHEET AS …


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NOTE that the file extension that will be added automatically to asaved Minitab worksheet is .MTW (that is, MiniTab Work s heet). Thisfile can only be accessed from Minitab.

To save your data (Minitab worksheet) as well as your results in the sessionwindow, you need to save these as a project file. To do this, you follow thesteps below:

Click on FILE and choose SAVE PROJECT A S … .

In the SAVE IN select the USB stick drive.

Note that it is important that you first save your work.

In the FILE NAME box you will see that the name MINITAB isenteterd by default. Delete this and givean appropriate name to youroutput file.

Note that in the SAVE AS TYPE: box you can see that this file is a MINITABPROJECT file and the file extension given to this file is .MPJ .

This file can be opened in Minitab only by selecting OPEN PROJECT fromthe FILE menu.

Click SAVE to save your project (that is, both d ata and results ).

[L] SAVING DATA AND RESULTS IN MINITAB .

[M] SAVING A GRAPH.

FILE SAVE PROJECT A S …

FILE SAVE GRAPH AS …


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After you have produced a high resolution graph then you can save this asfollows:

Click on FILE .

Select SAV E GRAPH AS … .

Note that Minitab has already given a name to your graph inside theFILE NAME: box . If you are not happy with the chosen name thenchange it by typing a name of your choice.

In the SAVE IN: box , choose the drive of your choice.

Note that in the SAVE AS TYPE: box the f i le extension that will be givento a Minitab graph is .MGF.

Click on SAVE to save your graph.

You can open a graph that you have previously saved as follows:

Click on FILE .

Select OPEN G RAPH … .

In the LOOK IN: box choose the drive on which you have saved yourgraph.

Highlight the graph name you want to retrieve.

Click on OPEN .

Click OK .

[N] OPENING A SAVED GRAPH.

FILE OPEN G RAPH …


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Highlight your results in the session window.

Right click the mouse.

Select COPY .

Go to Microsoft Word and open the file containing your report.


Select PASTE .

After producing a high resolution graph, follow the steps below in copyingyour graph in Microsoft Word:


Select COPY GRAPH .

Go to Microsoft Word and open the file containing your report.


Select PASTE .

If you have made any changes to the data file make sure you save your filebefore exiting Minitab.

[O] COPYING THE RESULTS IN MICROSOFT WORD.

[P] COPYING A GRA PH IN MICROSOFT WORD.

[Q] EXITING MINITAB .

FILE EXIT


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Click on FILE .

Choose EXIT.

A dialog box appears, asking you if you want to save changes made to thisproject (that is, worksheet and output in the session window).

Click the appropriate button according to your choice.

Note that:

If your response is YES then you will be given the chance to saveyour work (that is, you will be given the chance to save both the dataas well as your results).

Minitab refers to this as a PROJECT and the file extension that will begiven to your file will be .MPJ (that is, M initab Pro J ect).

If your response is NO then you will automatically exit Minitab.

Documents

Lecture Minitab Part 1