Minitab Interactive Example

The example given here is from MINITAB on Steel.

In this section, an interactive annotated example will be given to do 3 tasks:

  1. List the data for grade, years of computing experience, and total for math attitude scale;
  2. Do a one-way analysis of variance with grade as the independent variable and math attitude as the dependent variable; and
  3. Do a simple regression with years computing experience as the independent variable and the math attitude as the dep. variable.

The data was collected in the course of a study to investigate the computer anxiety in middle school children. The information collected from each student is: identification number, gender, school system, previous computer experience, scores on two 10-item Likert type questionnaire (mathematics attitude scale, computer anxiety scale), math test score, and computer test score. The data file, clas.dat, is stored in the default directory.

Now, let's have a quick look at the external data set, clas.dat. You may find that the data means nothing to you unless it has proper explanation. (The original clas.dat has 50 cases. For the sake of simplicity, here only 10 cases are listed.) Notice that line 8 has * meaning "missing value". (Minitab cannot take a blank or a period as the "missing value".)

01F1111115155222521412344423028
02F1111212155125521522244422825
03F2111124254214445155511144531
04F2121442322232245155511244243
05F1121541221241244145412154844
06F1122124254224544145412155040
07F2122224144225555155511244033
08F2222***244224421412234422932
09F2222115155115421412244412524
10F2222114155124544154511159925

To start your Minitab session.

To execute an interactive Minitab job, at the system prompt, type:

   minitab

You will see the MINITAB system information and a MTB> prompt as:

MINITAB Statistical Software, Standard Version
Release 9.1 for SUN
(C) Copyright 1992 Minitab Inc. - All Rights Reserved

JUNE 14, 1999 - INDIANA UNIVERSITY

Worksheet size: 100000 cells
  
  For information on:            Type:
  --------------------------     ---------------
  How to use Minitab             HELP
  Customer service               HELP OVERVIEW 14
  Documentation                  HELP OVERVIEW 15
  What's new in this release     NEWS


MTB> 


Comment is given for each command and is placed after the '#' sign.

MTB> READ 'clas.dat' c1-c28;

# READ accepts the data from external file and assigns the data into
# 28 columns/variables.  The semicolon (;) tells the system to wait 
# for the subcommand.

SUBC> FORMAT (f2,a1,24(f1),2(f2)).

# FORMAT specified the way to read the data file.  f2 means to read 
# 2-digit number for the first column, whereas a1 means to read a 
# character from the data file.  24(f1) means to read a 1-digit number 
# for 24 times, whereas 2(f2) means to read a 2-digit number twice.  
# The subcommand must end with a period.

MTB> NAME C1 'ID' C2 'SEX' C3 'AGE' C4 'GRADE' C5 'EXP' C6 'COUNTY'

# NAME assigns descriptive name to one or more columns/variables.  The
# descriptive name must be included in the single quotes and must be no 
# more than 8 characters. No space is allowed inside of the single quotes.

MTB> NAME C7 'COMP1' C8 'COMP2' C9 'COMP3' C10 'COMP4' C11 'COMP5' C12 'COMP6'
MTB> NAME C13 'COMP7' C14 'COMP8' C15 'COMP9' C16 'COMP10'
MTB> NAME C17 'MATH1' C18 'MATH2' C19 'MATH3' C20 'MATH4' C21 'MATH5'
MTB> NAME C22 'MATH6' C23 'MATH7' C24 'MATH8' C25 'MATH9' C26 'MATH10'
MTB> NAME C27 'MATHSCOR' C28 'COMPSCOR'

# C7 to C16 are the individual scores for computer opinion survey questions.
# C17 to C26 are the individual scores for math attitude scale questions.
# C27 is the score in math and C28 is the score in computer science.

MTB> LET C29= C17 + C18 + C19 + C20 + C21 + C22 + C23 + C24 + C25 + C26
MTB> NAME C29 'MATHATTI'

# These 2 lines of MINITAB code create C29 as the sum of all math 
# attitude scores, then assign it to a descriptive name, 'MATHATTI'.

MTB> PRINT 'grade' 'exp' 'mathatti'

# PRINT will print one or more columns/variables on the screen.  The 
# variable must be inside of single quotes.

MTB> AOVONEWAY of the 'mathatti' in 'grade'

# AOVONEWAY performs a one-way analysis of variance with grade as the
# independent variable and math attitude as the dependent variable.

MTB> REGRESS 'mathatti' on 1 predictor 'exp'

# REGRESS performs a simple regression with years computing experience 
# as independent variable and the math attitude as the dependent variable.

MTB> STOP

To end your Minitab session.

All the work you did will be lost when you exit Minitab. To store your output file, at the beginning of the Minitab session, type:

	MTB> OUTFILE 'myfile.out'

To save all the command lines you enter during a Minitab session, at the Minitab prompt, type:

	MTB> journal = 'myfile.inp'.

NOJOURNAL command will stop recording input lines.

You may read in an already created Minitab command file into a Minitab session. To read in an existing file, from your directory, to a Minitab session, at the MTB > prompt, type:

	MTB> EXECUTE  'myfile.MTB'

For more information in working with Minitab contact the UITS Stat/Math Center (812/855-4724, email: statmath@iu.edu).

You may also access Minitab from under Windows, or Macintosh environment from the UITS Student Technology Center (STC). Contact UITS Stat/Math Center for further information.