rd4_1a

Chi3_1doc

Rev Jan 2, 1998

Babson College
F.W. Olin Graduate School of Business

Chicago Fashion Study I: Using MiniTab to Graph the Data

You have learned a variety of techniques for using MiniTab to process study data. This note focuses on how to Graph your cross-tabulations. This is important because graphs are often the most effective way to present such tabular data. The note reviews how to make cross tabulations and then addreesses:

Graphing Cross Tabulations, and
Annotating/Coloring the Graph.

Making Cross Tabulations.

In an earlier note, you learned to use MiniTab to tally and cross-tabulate the data. Let's review how to cross-tabulate age and price of dresses, for example. Select "Stat, Tables, Cross Tabulation"; click on your first variable (in this case, 'AGE') and "Select"; then click on your second variable (in our case 'CODE_DRS'), and "Select" again. The dialog box will look like this:

(NOTE: MiniTab wants the "ROW" variable listed first. In this example this is ‘Age’.)

Note that we have "X"ed the box labeled "Column Percents" and the box labeled "Chi-square Analysis". Those commands produce the cross tabulation table shown below:

Tabulation of CODE_DRS by AGE

CHI-SQUARE = 44.545 WITH D.F.= 15
CELL CONTENTS --
% OF COL
COUNT

Graphing Cross Tabulations.

To graph the table shown above, proceed as follows, beginning in the Graph Variables section:

Click on GRaph/Chart. You will get the Chart screen shown below.
Click on the triangle next to "Function" and then select "N" from the list
The cursor will move to the "Y" column and the list of variable will appear in the dialogue box on the left of your screen.
Highlight and Select your "Y" variable -- (in this case the column variable from the Table command, above) -- C_75 'CODE_DRS'.
The cursor will move to the "X" column. Highlight and Select your "X" variable --(in this case the row variable from the Table command above)--C40 'AGE'.

Now work on the "Data display" section of the dialogue box:

In row 1, under Display, look for the word "BAR". If it is not there, click on the triangle and select "Bar".
Click on the triangle under Group variables and select "Group".
Select or Copy the "Y" variable -- 'CODE_DRS' from above to the Group variables section.

Now click on "Options" and the Chart Screen will appear.

Click on the check-mark in front of "Stack", to make a bar chart.
Click on the check-mark in front of "Total Y to 100% ....".
Click on "OK"... to go back to the Chart screen.
Click on "OK" again... In a few seconds the following Chart will appear.

At this point you can review the graph andre-run it to make changes. One of the changes that researchers often make at this point is to "reverse the axes" to get more meaning out of the data. To do so, just repeat the above steps with the X and Y variables reversed.

Annotating/Coloring the Graph.

You can also use the "Annotations" button to get access to additional screens to add titles and other annotations. Most are obvious. So just give it a try.

You can also determine how the Graph is shaded or colored. Just cklick on "Edit Attributes" and change the shading assigned to the "Group Variables" selected above. Experiment.

You can them make and save the Graph by clicking on "OK" and Clicking on "File/Save" or "Save as" and saving it for future use. Or you can click on "Alt/PrintScreen" and copy/paste it to a .doc or .ppt file.

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