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					GUIDE TO MINITAB


   Prepared by Maria Rios




    BUSINESS STATISTCS

           41000

      C. ALAN BESTER

         FALL 2009
FALL 2009                                                BUSINESS STATISTICS 41000


1. INTRODUCTION

Minitab is a Statistical Analysis software that allows to easily conduct analyses of
data. This is one of the suggested software for the class. This guide is intended to
guide you through the basics of Minitab and help you get started with it.

2. USING MINITAB

   2.1. Using Minitab in Harper and Gleacher Center

   Minitab can be found in the computer lab computers. In order to load the
   software go to:

   START -> PROGRAMS -> MATH & STATS -> MINITAB 15 -> MINITAB 15
   STATISTICAL SOFTWARE ENGLISH




   2.2. Using Minitab in your Computer

   You can use Minitab 15 on your computer by taking advantage of the academic
   agreements Minitab 15 has. All the information can be found in

   http://www.mintab.com/en-US/academic/licensing-options.aspx

   2.3. Minitab Resources

   The main source of help for Minitab can be
   found in the built-in help menu. For it go to
   HELP -> HELP.



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   Additionally, there are several useful Minitab Resources.

   1. Meet Minitab

   http://www.mintab.com/uploadedFiles/Shared_Resources/Documents/MeetMi
   nitab/MeetMinitabEN.pdf

   2. Minitab Tutorial – University of Reading

   http://www.reading.ac.uk/nmsruntime/saveasdialog.aspx?lID=35672&sID=143
   849.

3. STARTING MINITAB
   3.1. Minitab Project and Worksheets

   Minitab has two main types of files, projects and worksheets. Worksheets are
   files that are made up of data; think of a spreadsheet containing variables of
   data. Projects are made up of the commands, graphs and worksheets. Every time
   you save a Minitab project you will be saving graphs, worksheets and
   commands. However each one of the elements can be saved individually for use
   in other documents or Minitab projects. Likewise you can print projects and its
   elements.

   3.2. Understanding the interface
        After loading Minitab, you will either open an existing project or a new one.




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         In either case, the following window structure appears
           Menu
           bar
             Toolbar




                       Session
                       Window




                       Worksheet
                       window




        There are 4 areas in the screen, the Menu bar, the Toolbar, the Session
        Window and the Worksheet window.

        3.2.1. The Menu bar: You can open menus and choose commands. Here you
             can find the built-in routines1.

        3.2.2. The Toolbar: Shortcuts to some Minitab commands.

        3.2.3. Session Window: Displays output and
             lets you type commands. In order to be
             able to type commands in the Session
             window you need to enable2 this option.
             To do so go to

        EDITOR -> ENABLE COMMANDS.

         The Session Window will now look like




1 Minitab has a large number of built-in routines that allows you to do most of the basic data analysis.
Commands can also be typed into the Session Window, to either replicate the built-in routines or to
create a more tailored data analysis.
2 The “MTB>” prompt should be visible in the Session Window.




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        It is recommended to always perform this step when you first you get into
        Minitab.

   3.3. Worksheet Window:

        Data in Minitab is stored in a worksheet of columns and rows. Typically,
        each column contains the data for 1 variable, with 1 observation in each
        row. Columns are numbered C1, C2, C3, … , while rows are numbered 1, 2, 3,
        …

       3.3.1. Changing column name.

       You can change column names by clicking the field below the column
       number, typing the name and then hitting return. You can also change the
       name using commands (see section 10.2.2)

       3.3.2. Editing column data.

       Column data can be edited. You can also copy and paste data into the
       columns. You can paste .txt and Excel data with no problem.

4. LOADING DATA IN MINITAB

Minitab files are organized as “projects”. Each project will contain all the data you
use and the commands and analysis you perform on the data.

You can open a new, empty worksheet at any time. In this empty worksheet you can
copy, paste and type the data you need by simply working on the worksheet as you
would on any spreadsheet.

   4.1. Opening an existing Worksheet (Minitab type file)

   Within a project you can open one or more files that contain data. When you
   open a file, you copy the contents of the file into the current Minitab project. Any
   changes you make to the worksheet while in the
   project will not affect the original file.

   To open a Minitab type file
   1. Choose FILE -> OPEN WORKSHEET


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  2. Look for the file you want to open. Should be a .MTW or .MPJ type file. Select
     the file and click Open.
  3. If you get a message box indicating that the
     content of the file will be added to the current
     project, check “Do not display this message
     again”, and then click OK.



  4.2. Importing data (Non – Minitab type files)
     4.2.1. Opening Excel files
     1. Choose FILE -> OPEN WORKSHEET
     2. In the field “File of Type” select EXCEL (*.xls,
         *.xlsx) from the drop down menu.
     3. Choose the file you wish to open, and click
         Open.
     4. If a message box appears see step 3 of opening
         an existing Minitab Worksheet (see section
         4.1, 3)

     4.2.2. Opening a text file
     1. 1. Choose FILE -> OPEN WORKSHEET
     2. In the field “File of Type” select TEXT (*.txt)
         from the drop down menu.




     3. Click OPTIONS and the following dialog box will appear.




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     4. Go to the “SINGLE CHARACTER SEPARATOR” option. The data on the text
        file is usually separated by spaces or tabs. Choose the appropriate option.
        If you are unsure how the data is separated, another option is to use the
        number of data rows. Just introduce the number of data rows in the
        “NUMBER OF DATA ROWS” box.
     5. Click OK.
     6. The results will appear in the worksheet window.




     Note: This can be sometimes a little tricky as you can get a file that does not
     the have the data in the format that you want. If this happens, close the
     worksheet where the data is placed and try importing it again, changing
     some of the options in step 4. This is a trial and error procedure; so don’t
     panic if you don’t get it in the first attempt.

     4.2.3. Copying data to Minitab
     Copying data to Minitab works like copying data to any other type of
     spreadsheet (eg. Excel).

     1. Copy the data you wish to use in Minitab.
     2. Go to the position where you want to copy the data in the desired Minitab
        worksheet. If you wish to paste a cell with a Header or Name, make sure
        that you stand in the variable name cell (cell below the number of the
        column C1, C2, etc).
     3. Go to EDIT -> PASTE CELLS to paste the data.
     4. Sometimes when you copy data, Minitab reads it in a wrong format, eg. As
        a text when is numeric. To solve this problem, select the problematic
        column(s) and go to DATA -> CHANGE DATA TYPE -> CHOOSE THE
        DESIRED FORMAT. The most useful format is numeric.



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      The following dialog box appears.
      Choose the variables you want to
      modify and where you want to store
      them. The storage variables can be the
      same variables as the ones you are
      modifying. Then hit OK.




5. Ways to Analyze Data

Analysis in Minitab can be done in two ways: using the Built-In routines or using
command language in the Session window. These two can be used interchangeably.

   5.1. Built-In routines

   Most of the functions needed in basic and more advanced statistical analysis are
   found as Minitab Built-In routines. These routines are accessed through the
   menu bar. To use the menu commands, click on an item in the menu bar to open
   a menu, click on a menu item to execute a command or open a submenu or
   dialog box.

   5.2. Command Language

   To be able to type commands in the Session window, you must obtain the
   “MTB>” prompt (See section 3.2.3). All commands are then entered after the



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   “MTB>” prompt. All command lines are free format, in other words, all text may
   de entered in upper or lowercase letters anywhere in the line.

NOTE: This guide focuses mainly on using the Built-In routines. All the
explanations and examples that follow will be done using Minitab’s Built-In
routines. A brief introduction to using Minitab commands is found in section
10.

6. Descriptive Statistics
   1. To obtain descriptive
      statistics of a variable or set
      of variables, go to

       STATS -> DISPLAY
       DESCRIPTIVE STATISTICS




   2. And a prompt window should appear. In the
      window select the variable(s) you want to
      analyze and click ok.




   3. Results will be presented in the Session window as follows.




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7. Graphs

Graph drawing built-in routines in Minitab can be found
under the GRAPH menu in the menu bar. On the Graph Menu
you have several types of plots that you can choose from, and
that you can use to produce your desired plot. Below is an
explanation of how to use the most popular graph routines.

Minitab graphs will appear as separate windows that are
considered part of the project, however they can be saved
and copied for use in documents. Plots can be customized by
modifying the plot options.

   7.1. Simple Scatterplot
   1. For a simple scatterplot, go to the
      SCATTERPLOT submenu. The following
      dialog box appears.



   2. Choose the simple type of scatterplot, (the
      with regression type is also common).




   3. The following dialog box
      appears. Choose the variable
      to go on the y-axis and the
      variable to go on the x-axis,
      and click OK.




   4. Minitab will produce a plot
      as shown here.




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  7.2. Simple dotplots
  1. For a simple dotplot, go to the
     DOTPLOT submenu. The following
     dotplot dialog box appears.




  2. Choose the Simple dotplot
     and the following dialog box
     appears. Choose the variable
     you want to plot and click
     OK.




  3. Minitab produces a plot as
     shown here.




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  7.3. Simple Histogram and Simple Histogram with fit
  1. For a simple or simple with fit histogram, go to the HISTOGRAM submenu.
     The following histogram dialog box will
     appear.
  2. Choose the type of histogram you want.




  3. The following dialog box
     appears. Choose the variable you
     wish to plot and click OK.




  4. Minitab will produce plots as presented below, according to the type of
     histogram chosen.




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  7.4. Simple Time Series Plot
  1. For a simple time series plot, go
     to the TIME SERIES PLOT
     submenu, and choose simple
     from the dialog box.




  2. The following dialog box
     appears. Choose the
     variables to be plotted and
     click OK.




  3. Minitab produces a plot as
     follows.




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8. Basic Statistics for pairs of variables

In order to calculate basic statistics for
pairs of variables, like covariance and
correlation, go to STAT -> BASIC
STATISTICS

In this document examples of statistics
are calculated assuming only two
variables are being analyzed, however
pair wise statistics for more than two
variables can be calculated by simply
adding all the desired variables to the
“VARIABLES” box in the dialog
windows.




   8.1. Covariance
   1. Choose COVARIANCE to obtain the
      following dialog box. Pick the pair of
      variables you wish to analyze and click OK.




   2. The result will be presented in the Session
      window as presented below.




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   8.2. Correlation
   1. Choose CORRELATION and obtain the
      following dialog box. Choose the pair of
      variables to be analyzed.




   2. Results are displayed in the Session window as
      presented below.




9. Doing Calculations with variables

Minitab allows you to do calculations with the
variables that you are using. For example you can
add and multiply variables. In order to do these
calculations you should go to CALC ->
CALCULATOR




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The following dialog box appears

This is basically a calculator that allows
doing many calculations with the
variables. Basic functions are found in
the number pad and more sophisticated
ones are found in the functions box to
the right of the number pad.

To make sure that your results is not
overwriting a variable, name a new
variable in the “STORE RESULTS IN
VAVRIABLE” field in the top of the
calculator.

   9.1. Adding variables
   1. To add variables name the variable
      where you want to store the results.
   2. Select the first variable, press the
      “+” sign and select the second
      variable (and so on for more than
      two variables). You should obtain
      something similar to the window in
      the right




   3. The result will then be shown in the worksheet window




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  9.2. Taking logarithms

  Another useful function in statistical analysis is to take logs of variables.

  1. Look for the “NATURAL LOG” or “LOG BASE 10” (depending on the one you
     need) in the function list. A shortcut
     to finding the functions is to choose
     “LOGARITHM” from the function
     drop down menu.
  2. Inside the parenthesis, change
     number for the variable name.
     Highlighting “NUMBER” and hten
     selecting the variable you want to
     modify does this.
  3. Make sure that you have defined a
     variable where you want to store
     results, by putting the name in the
     “STORE RESULT IN VARIABLE” box.
  4. The result will appear in the
     worksheet window.




  9.3. Logical functions

  Some statistical analysis will need to separate by groups according to
  characteristics that are contained in the data. Logical functions are particularly
  useful in these cases. A simple example on how to use them is described below.




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   1. Choose the variable you want to do the logical test to. Here we are looking at
      the “SEX” variable.
   2. Choose the logical test you want to use. Here
      we want to see which observations have the
      variable “SEX” equal 1. That is, which
      observations are males.
   3. Make sure that you have indicated a variable
      in which to store your results, by typing the
      name of your result variable in the “STORE
      RESULT IN VARIABLE” box.
   4. The result variable will be a binary variable
      (variable of 1s and 0s) where 1 indicates the
      logical test is true and 0 the test is false. The
      result variable will appear in the Worksheet
      window.




10. Using Minitab commands in the Session Window

Minitab commands can only be written after the “MTB>” prompt. If this prompt is
not visible in your Session Window, you need to enable commands, see section 3.2.3.

   10.1.     Minitab command language

   For Minitab to understand the commands you are typing you need to have in
   mind the following conventions, otherwise Minitab will not produce results.

   1. Variable names must go inside ‘ ‘. This means that is you are referring to a
      variable named AGE you will need to type ‘AGE’ every time you are referring
      to it in a command line.
   2. When you are referring to the number of a column you don’t need to type ‘ ‘.
      For example if you are using variable C1, you will only need to type C1.
   3. Before doing a variable calculation you must type



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     Let variable_name =

     In the variable_name field you can either use the number of the column or
     the name of the variable.

  4. Whenever you are using a character or group of characters you need to use
     ‘ ‘. For example if you want to name variable C1 as AGE you need to write
     “AGE”.
     10.1.1. Help with Minitab Commands
     1. If you need help with the Session Command window or Commands go to
     2. HELP -> HELP (See section
           2.3)
     3. Then under REFERENCES
           click SESSION
           COMMANDS, then
           SESSION COMMAND HELP.
     4. Click on the link SESSION
           COMMAND HELP that
           appears on the right hand
           side window




     5. The following window appears. There you can find functions and general
        help for Minitab Commands




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  10.2.      Examples
     10.2.1. Adding variables
     1. To add variables type in the command window

     Let RESULT_VARIABLE =
     VARIABLE1_NAME +
     VARIABLE2_NAME

     Suppose you want the
     variable test to be equal to
     age + sex, then you must type

     Let ‘test’ = ‘age’ + ‘sex’
     2. Results will appear on the
        worksheet window in the
        test column.



     10.2.2. Naming a variable
     1. Type in the session window

     Name COLUMN_NUMBER “NAME”

     Suppose that you want to name
     test column C8 then you need to
     type

     Name C8 ‘test’

     2. Results will appear in the
        worksheet.



     10.2.3. Taking logs
     1. To take (natural) logarithms of a variable type

     Let RESULT_VARIABLE =
     LN(VARIABLE_NAME)

     Suppose you want to have
     (natural) logarithms of age
     stored in column C9. Then
     you must type




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      Let C9 = LN(‘age’)

      2. Results will be shown in the worksheet window



11. REFERENCES
    1. Minitab. Meet Minitab 15. 2007
    2. Federico Bandi. Introduction to Minitab. Summer 2009.




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