Getting Started with Minitab 14 for Windows - ISS - University of Leeds

Information Systems Services
Getting started with Minitab 14
for Windows
November 2004

Getting started with Minitab 14
for Windows
Contents
Introduction .......................................................................................................................... 3
Aim of this Document ....................................................................................................... 3
Prerequisites .................................................................................................................... 3
Example Files ............................................................................................................... 3
The Minitab Environment ................................................................................................. 3
The Project Manager .................................................................................................... 4
Issuing Commands ....................................................................................................... 5
The Menu Bar ............................................................................................................... 5
The Toolbars ................................................................................................................ 7
Dialog Boxes ................................................................................................................ 8
Session Commands ...................................................................................................... 8
The Help System .......................................................................................................... 9
Projects .............................................................................................................................. 11
Opening a project and its parts ...................................................................................... 11
Saving a project and its parts ......................................................................................... 12
Minitab Data ....................................................................................................................... 13
Working with Data .......................................................................................................... 14
Missing Values ............................................................................................................... 16
Printing ............................................................................................................................... 28
Feedback: If you notice any mistakes in this document please contact the Information
Officer. Email should be sent to the address info-officer@leeds.ac.uk
Copyright: This document is copyright University of Leeds. Permission to use material in
this document should be obtained from the Information Officer (email should be sent to the
address info-officer@leeds.ac.uk)
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Introduction
Minitab is an easy-to-use, flexible yet powerful package, for use on personal computers,
which performs a wide range of statistical analyses. It is especially suitable for students
and researchers who are not familiar with using a computer. The number of worksheets
that can be opened at one time is only limited by the computer’s memory. By default it can
handle 100,000 cells or data items, some of which may be missing values. Data may
either be entered via the PC’s keyboard or retrieved from a file on disk, and may then be
modified, transformed and saved on file from within Minitab. Printed copies of results
appearing on the screen may be produced for examination at leisure. Minitab is largely
self-documenting through its help facility, so that only a minimum of preparation is needed
in order to use the package.
Aim of this Document
This document provides an introduction to using the Minitab statistics package (version 14)
for first-time users. The document describes the Minitab Environment and explains the
basic features of the package.
Prerequisites
This document assumes that you are familiar with the use of Microsoft Windows
applications and logging on to the ISS Desktop. If you are not, please consult the
document Getting Started With Microsoft Windows. It is also assumes that you are familiar
with basic statistical terminology.
Example Files
To download the example files: open a web browser such as Internet Explorer and go to
URL: http://iss.leeds.ac.uk/software Click on PDF files, choose Statistical Analysis
and scroll down to the Example Minitab file. Save the file to your local hard disk, then
double click on it to open the Zip file.
The Minitab Environment
When Minitab starts, a new project is opened automatically, and three windows will be
visible:
• Data window
• Session window
• Project Manager (minimised at startup)
The project file contains worksheets that contain the data, data windows that display the
data, a session window that contains the results of analysis, graphs created with Minitab’s
Graph command, toolbars for issuing commands, a status bar and a Project Manager.
Many windows may be displayed, but only one of them will be active. The active window
will show three asterisks next to the title.
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Figure 1 Active Data Window
The windows can be accessed from the Window menu, by clicking on their title bar or
using the appropriate shortcut keys:
Window Shortcut Note
Data
Session
Project Manager
Command Line Editor See section 1.3.6
The Project Manager
This contains a series of folders:
Folder Purpose
Session Management of session window output
History Stores a list of commands generated in the current
session
Graphs Management of graphs
Report Pad Creating and editing reports of Minitab work
Related Documents Contains project related, non Minitab files
Worksheets Stores individual folders for any open worksheets.
Each of these displays a summary of the data used in
the worksheet
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Figure 2 The Project Manager Window (Report Folder Selected)
Issuing Commands
There are three ways of accessing Minitab commands: through the menus; through the
toolbar; or using session commands. However a command is issued, it always acts on the
data in the current worksheet, i.e. the active Data window. To make a window active, click
on it or choose it from the Window menu.
The Menu Bar
This gives access to all the Minitab commands.
Figure 3 The Menu Bar
To run a command from the menu bar, click on the menu to open a submenu and then
select the required commands. The main menus are:
Menu
Item
Function Shortcut
Key
File Open, save and print and close projects and their
components.
Edit Cut, Copy and Paste commands, access to the
Command Line Editor and links to external
documents.
Data Commands to manipulate worksheet, such as
Merge Worksheets, Sort, Split and Change Data
Type.
Calc Commands to calculate mathematical
expressions and transformations, generate
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datasets, calculate row and column statistics and
manipulate matrices.
Stat This menu contains all the statistical commands.
Graph Commands to generate and modify a wide variety
of graphs.
Editor Items in the Editor menu depend on which
window is currently active. For example, when the
Data window is active it contains commands to
format data and insert rows or columns.
Tools Allows access to Windows Explorer, Microsoft
calculator, notepad and selection of the Minitab
toolbars. It also contains hyperlinks to the Minitab
knowledge base, and allows the user to
customise the Minitab interface.
Window Selects a new active window and alters the way
the windows and other items are displayed.
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Help Help items. These will be described section 1.3.7

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The Toolbars
These provide access to the most commonly used functions. If a toolbar is not currently
displayed, click Tools > Toolbars and then select the appropriate one. Repeat this process
to hide a toolbar. Alternatively, right-click the mouse to switch the toolbar on or off.
The commands available on a toolbar depend on the active window. Pointing the mouse
cursor at a button on a toolbar will cause its function to be displayed.
The Project Manager toolbar provides shortcuts to all the Project Manager folders.
Figure 4 Toolbars
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Dialog Boxes
Many commands will generate dialog boxes. Minitab dialog boxes will often have a
variable list box, which displays columns, stored constants or matrices. When a text box
requires a variable, select one from the list of all valid variables in the current worksheet
and double-click on it to fill the text box. (Alternatively, click once to select it and then click
the Select button.)
Figure 5 Dialog box with Height variable selected
Session Commands
Experienced Minitab users may wish to use the command style. Commands can be typed
either into the Command Line Editor or into the session window. To use the Command
Line Editor, select Edit > Command Line Editor () from the menu. This will open a
new window, into which the commands can be typed. To enter commands in the Session
window choose Editor > Enable Commands from the menu. The MTB> prompt will then
appear in the Session window. When the MTB> prompt is present, any analysis carried
out using menus and dialog boxes will result in the corresponding commands being
recorded in the Session window. The session window may then be saved as a separate
file to be reused at a later date. For more information about the Minitab command
language choose Help > Session Command Help from the menu.
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The Help System
A comprehensive help system is available from the Help menu, and the Help files are in a
printable format.
In addition to complete menu and dialog box documentation, there are overviews,
examples, guidance for setting up your data, information on calculations and methods, and
a glossary.
Item Description
How to use
Help
Explains the organisation of the help system.
StatGuide Provides statistical guidance for interpreting statistical
tables and graphs in a simple, practical way.
Tutorials These step-by-step tutorials introduce the Minitab
environment and provide a quick overview of some of
Minitab’s most important features. Each tutorial is designed
to explain the fundamentals of using Minitab, e.g. how to
use the menus and dialog boxes, how to manage and
manipulate data and files, how to produce graphs. There
are five tutorials: Graphing Data, Entering and Exploring
Data, Analyzing Data, Assessing Quality, Designing an
Experiment. Sample files are available for use with these.
Session
Command
This provides information and the command syntax for all
session commands, indexed alphabetically and by function.
Macros Illustrates how to use the commands and describes the
different types, rules to follow, formats and capabilities.
Contains a list of macros arranged by function .
Minitab on the
Web
Contains a hyperlink to Minitab’s website:
www.minitab.com/
Keyboard Map Has a list of all the shortcut keystrokes that can be used in
place of menu commands.
About Minitab Contains the product name, release number, serial number,
contact details and system information.
Meet Minitab Documentation can be downloaded in PDF format from
www.minitab.com/resources/tutorials
Note: Further online resources and downloads are available from
www.minitab.com/resources
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Other Minitab documentation, including the Minitab Reference Guide and the Minitab User
guide, is available from the ISS Help Desk.
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Projects
An empty project is created automatically when Minitab is started. A Minitab project
consists of all parts of your work, including the text output (session window) from the
commands issued, the data stored in worksheets (viewed in the data windows) and any
graphs that have been created.
Projects can be opened and saved as a whole, or individual parts of a project can be
saved separately. Items, such as a worksheet or graph, can also be discarded from a
project.
Opening a project and its parts
Type Instruction Notes
project File > Open Project or
press
worksheet File > Open Worksheet Available file types for data are:
Excel, Quattro Pro, Lotus 1-2-3,
and dBase files.
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For MS Windows programs, DDE
(dynamic data exchange) can be
used to import data into Minitab.
worksheet File > Other Files > Import If the data required are not from
these applications, save the data
in a text file. Most applications can
create text files. Minitab can open
plain text (ASCII) files, which
usually have an extension of TXT
(for text) or DAT (for data).
worksheet File > Query Database
(ODBC)
graph File > Open Graph
If the other application is a
database, then ODBC can be
used. It may be necessary to
include a new data source if the
required on is not present in the
Select data Source dialog box.
Note: When a worksheet or graph is opened, the data are copied to the open project. Any
changes made to the worksheet or graph are not automatically saved to the worksheet or
graph file, even if the project is saved.

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To save changes to the individual files, save the worksheet or graph separately.
Saving a project and its parts
To save a project, choose File > Save Project As… from the menu. Type in a filename in
the File name: box and choose a suitable directory to store the file in and click Save. The
first time a file is saved, choosing File > Save Project from the menu (or pressing CTRL+S)
has the same effect as using File > Save Project As… Once the project has been named,
using File > Save Project will automatically overwrite the existing file without requiring entry
of a file name.
To save the individual parts of a project choose:
Type Instruction Notes
Project File > Save
Project As…
Worksheet File > Save
Current
Worksheet As…
Session
Window
File > Save
Session Window
As…
Graph File > Save Graph
As…
History file TXT, MTJ
Minitab Project (MPJ)
Available file types are: Minitab worksheet
(MTW), Minitab 12, 11, or 10 worksheet
(MTW), Portable worksheet (MTP) , Text
file (DAT, TXT) , Excel file (XLS), Lotus 1-2-
3 files (WK?), Quattro Pro file (WB1,
WQ1), dBASE/FoxPro file (DBF), Web
Page (HTML).
Mintab Session (TXT), Rich Text Format
(RTF), Web Page (HTML), List File (LIS).
The default graph type is MGF (Minitab
Graph). Other types are also available:
JPEG (Joint Photographic Experts Group),
TIFF (Tagged Image File Format), PNG
(Portable Network Graphics), BMP
(Windows Bitmap). For high quality printing,
use EPS (encapsulated postscript). Note
that an EPS file cannot be viewed in a word
processor.
Note: It is good practice to save a worksheet as a separate file, so that it will be stored
safely even if the project is corrupted.
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Minitab Data
In Minitab, data are contained in a worksheet. This looks similar in appearance to a
spreadsheet, but in Minitab cells do not contain formulae that update results automatically.
If a calculated variable is created from existing variables, and then the value of one of
those variables is updated, the value of the calculated variable will not be updated
automatically. A Minitab project may contain several worksheets. Rows in the worksheet
represent cases. Columns represent attributes of the cases and are known as variables.
Quantitative variables are measured on an ordinal, interval, or ratio scale; for example,
measuring heights and weights. Qualitative (categorical) variables are measured on a
nominal scale; for example gender or machine number. During an experiment,
“independent variables” or factors are set by the experimenter; while “dependent variables”
are observed and measured.
There are three types of data:
• Numeric numbers
• Text text, numbers, spaces or special characters
• Date / Time dates e.g.1/1/04, times e.g. 10:20:30AM or both
Note: Although dates can be formatted in a variety of ways, Minitab stores them internally
as numbers and so they can be used in calculations.
Data can take three forms:
• Column
• Constant
• Matrix
Columns may consist of numbers, text or date / time data. A column can be referred to
either by the letter C followed by a number, e.g. C1 or by a variable name.
Constants may contain a single number or a text string e.g. “Paris”. A constant can be
referred to either by the letter K followed by a number, e.g. K22, or by a variable name.
Matrices contain a rectangular block of numbers, and may be referred to either by the
letter M followed by a number, or by a variable name.
The following restrictions apply to variable names:
• The length may not exceed 31 characters
• They must not begin or end with a blank
• They must not include the symbol ' or #
• They may not begin with, or consist entirely of, the symbol *
• They must not be repeated: the same name cannot be used for two variables
(columns, stored constants or matrices) in the same worksheet
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Working with Data
Three windows can be used to work with data: the Data window, the Worksheet folder and
the Session window.
The Data Window contains columns of data that are in the worksheet. If multiple
worksheets are open, each has its own data window, where the data can be viewed,
edited or manipulated.
Figure 6 The Data Window
The Worksheet Folder in the Project Manager summarises the columns, stored constants
and matrices in the current worksheet.
Figure 7 The Worksheet Folder
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The Session Window can be used to display the columns, constants and matrices. The
command Data > Display Data will open a dialog box.
Figure 8 Display Data Dialog Box
In Figure 8, the columns id and gender have been selected. (To select a variable, click on
its name in the left hand column and then click the Select button.)
Clicking on OK in the Display Data dialog box will cause the variable values to be
displayed in the session window.
Figure 9 Session Window showing id and gender Variables
Note: If the MTB> prompt is on, typing the command Print ‘id’, ‘gender’ in the session
window will achieve this result.
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Missing Values
In circumstances where information about a variable has not been collected for any
reason, the data item is said to be a missing value. The code for this is * if the item is
numeric, and a blank field if it is alphanumeric (text).
Most commands exclude from analysis all rows with a missing value and display the
number of excluded points. When an arithmetic command operates on a missing value,
Minitab sets the result to *.
Note: When * is entered as a value in the Data window it should not be enclosed in
quotation marks. However, the * must be enclosed in quotation marks when it is part of the
command line typed at the MTB> prompt.
Task 1 Entering Data in the Data Editor
Activity 1.1 Run Minitab by clicking Start > Programs > Statistics > Minitab14.
When Minitab opens, the session window and an empty worksheet will be
displayed. If the command prompt MTB> is not showing in the session
window, select Editor > Enable Commands. If the direction arrow in the
session window is pointing downwards, click once on it to change the
direction to right. (When the direction arrow points downwards, the effect of
pressing the key is to move the cursor down to the cell below the
current one. Normally data are entered by case).
Figure 10 The Direction Arrow Pointing Right
Activity 1.2 Enter the values Centre, Order, Arrival, Distance in the row immediately
under that which contains variable numbers. After each name is entered,
press the key to move to the next column. After the last value, type
to move to the next row. Enter the dataset shown below:
Figure 11 Sample Input Data
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When you have completed this task, the worksheet should resemble the one
shown in Figure 12.
Figure 12 Completed Worksheet
Note that the variable number for Centre has changed to C1-T to show that it
is a text variable, the variable numbers for Order and Arrival have changed to
C2-D and C3-D respectively to show that they are date variables, and the
variable name C4 is unchanged because it is a numeric variable. Note also
that where gaps were left in the data, Minitab has inserted asterisks to
indicate missing values.
Activity 1.3 The entry for the distance variable in the second case is incorrect, and
should show a value of 309. Correct it by selecting the cell and typing the
value 309.
Activity 1.4 Select File > Save Current Worksheet As… and name it Orders. Click .
Note that you will select a folder of your own, and so the contents of the
screen that you see may differ from this.
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Figure 13 Save Worksheet Dialog Box
Activity 1.5 Now the project should be saved. Select File > Save Project As… and name
the project Tutorial. Minitab will append the file extension MPJ automatically.
Once the project has been saved in this way, it will only be necessary to click
on the SAVE icon on the standard toolbar in order to save it again.
Activity 1.6 It would be useful to calculate a new variable to show delivery times. Select
Calc > Calculator from the menu and then complete the dialog box as shown
below. First enter the name of the new variable DeliveryTime. Click on the
variable Arrival and then click Select. Click on the minus sign in the
calculator. Click on the variable Order and then click Select. Finally, click OK.
(Note that a slightly shorter way of selecting variable names is to double-click
on them.)
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Figure 14 The Calculator
Activity 1.7 In Activities 1.1−1.5, the graphical interface was used to perform a variety of
tasks. Because we enabled commands before we began, the corresponding
code that Minitab created in order to execute the tasks has been printed in
the session window.
Figure 15 Minitab Command Language Statements
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Task 2 Descriptive Statistics
Activity 2.1 This time an existing file will be used. Click File > Open Worksheet, and
navigate to the directory in which you saved the data files for this tutorial.
Select the file Pulse.MTW. This file will now be displayed in another data
window. It may be necessary to rearrange the windows in order to view all of
its contents. The previous worksheet is still open, and by dragging the
windows it will be possible to see both. Note that only one of the windows is
the active window. The active window is the one which has three asterisks
after its title.
Figure 16 Active Worksheet Pulse.MTW
Activity 2.2 From the menu, select Stat > Basic Statistics > Display Descriptive Statistics.
Figure 17 Stat Menu showing Basic Statistics Sub-menu
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Activity 2.3 Double-click the variables Height and Weight to select them. Click the
Statistics button to display the available statistics and then click OK in both
dialog boxes.
Figure 18 Display Descriptive Statistics Dialog Box
The results will be displayed in the session window.
Figure 19 Results of Analysis
Activity 2.4 Scroll upwards in the session window to see the commands that have been
executed as a result of the menu selections.
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Task 3 Recoding Variables
Activity 3.1 The variable Sex is a numeric variable which uses the code 1 for male and 2
for female. A new variable, Gender will be created by recoding this variable.
Click Data > Code and select Numeric to Text from the sub-menu.
Figure 20 Data Menu
Activity 3.2 Complete the next dialog box as shown below. Note that when this first
appears, the left hand panel shows a list of variables in the current
worksheet. Click OK and the new variable Gender will be added to the
worksheet as C9-T.
Figure 21 Numeric to Text Dialog Box
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Task 4 Creating a Histogram
Activity 4.1 A histogram of the variable Height will now be created, with separate panes
for the groups male and female. Select Graph > Histogram from the menu.
Choose the option With Fit and click OK.
Figure 22 Histogram Dialog Box
Activity 4.2 Double-click the variable Height in the left-hand panel to select it and then
click the Multiple Graphs button.
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Figure 23 Variable Selection Box for Histogram
Activity 4.3 At the next dialog box, click the By Variables tab, and then double-click the
variable Gender. (Alternatively click once on Gender and then click the Select
button.)
Figure 24 Multiple Graphs Dialog Box
Click OK at both dialog boxes and the histogram will be displayed as a
separate graph window.
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Figure 25 Graph Window
Task 5 Editing a Graph
Activity 5.1 In order to edit a Minitab graph, it is necessary to double-click the area or
object that is to be modified. Double-click the title of the histogram to display
the Edit Title dialog box, make the modifications shown below and click OK.
Figure 26 Edit Title Dialog Box
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Activity 5.2 Now double-click the white panel area around the graph to produce the
required dialog box, and change the background colour. Click OK.
Figure 27 Edit Data Region Dialog Box
Activity 5.3 Double-click on the Normal Distribution line to open the Edit Distribution Fit
dialog box. Make changes to the colour and thickness of the line.
Double-click the bars to open the Edit Bars dialog box, and make changes to
the pattern and colour of the bars.
Activity 5.4 Experiment with editing the other areas of the chart. Other options include:
Edit Footnote, Edit Axis Label, Edit Table, Edit Graph and Figure Regions,
Edit Bars, Edit Panels and Edit Scale. An example of an edited chart is
shown below.
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Figure 28 Edited Histogram
Activity 5.5 This chart can now be saved for later use. A variety of graphics formats is
available. If the chart is to be used for a web page, a suitable file format
would be JPEG or PNG. Make sure that the chart is selected, or the required
option will not be available on the File Menu. Click File > Save Graph As…
Select the arrow to the right of the Files of Type box and choose JPEG. If
necessary, give the chart a different name and then click Save.
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Printing
The contents of any Minitab window can be printed. To print a window, select it by clicking
on it or selecting it from the Windows menu. An option to print that window will now be
available under the File menu. For example, to print a worksheet:
Select the appropriate data window and choose File > Print Worksheet (or CTRL+P).
Choose the options required to format the printed output and click on OK. The standard
Windows Print dialog box is displayed. Ensure that the correct printer has been selected in
the Printer Name box and click OK to print the window.
Depending on the active window, the following options will be available on the File menu:
• Print Session Window
• Print Graph
• Print Worksheet
• Print Report Window
• Print History Window
Note that the session window contains limited formatting. If required, its contents may be
copied and pasted into a Word Processor, where formatting can be applied.
Minitab does have a Report Editor, which allows formatting. Results may be copied from
the session window into the Report Editor, formatted, and then printed.
Task 6 Using the Report Editor
Activity 6.1 Scroll upwards in the session window until the results of the descriptive
statistics are displayed. Select the output and click Edit > Copy. Maximise the
Project Manager Window and double-click Report Pad. Click in the right hand
panel and select Edit > Paste. The results will appear in the report, and they
can now be edited.
Figure 29 Project Manager showing Report Pad open
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Activity 6.2 Select the title text and right click the mouse. From the context sensitive
shortcut menu, select Centre. Repeat this process to change the font size
and colour.
Figure 30 Shortcut Menu
Activity 6.3 Minimise the Project Manager window, and select the chart. Click Edit >
Copy Graph, and then maximise the Project Manager window. Click in the
report pad window and select Edit > Paste. The chart will now be displayed.
Activity 6.4 With the report pad selected, click File > Save Report As…Choose either RTF
(rich text format) or HTML (hypertext markup language), give the file a name
and click on Save.
Activity 6.5 Select File > Print Report Pad.
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Task 7 Quitting Minitab
You should always quit any computer program when you have finished your session.
Never switch off the computer without closing down Windows. Do not leave a computer
whilst you are still logged on to it as others may use your account and could damage your
files.
Activity 7.1 Before leaving Minitab make sure you have saved the components of your
work (see Section 2.2). To leave Minitab choose File > Exit or click on the
Close box in the top right-hand corner of the Minitab window. If you have
made any changes since you last saved your work, you are asked if you
want to save changes to your project before closing. Select Yes to save the
project, No to exit without saving, or Cancel to return to Minitab without
saving
Activity 7.2 After leaving Minitab, choose Start > Logout. You must always logout before
leaving your computer.
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