JMP Tutorial # 1 - Introduction to Data Entry in JMP and Univariate Displays for Categorical Data

The statistical software package we will be using is SAS-JMP Version 5. The program is available for use on your laptop,in the Mathematics and Statistics Computing Lab located in GI 328, and the computer cluster on the 1st floor of the library. This handout discusses some of the basics of JMP use and describes how to access data sets you will be working with in class andfor homework assignments. You will be required to download and print tutorials like this one covering its use before class as needed.
Starting JMP

Select JMP 5.0.1or 5.1, depending on what version you have, from the Start --> Programs menu.
Entering Data
Under the File menu select New and choose Data Table from the pull out menu. A new spreadsheet will appear with only one column (labeled Column 1). As a first example we will be working with the following data collected on people with aphasia. Aphasia is the impairment or loss of the faculty of using or understanding spoken language. Three types have been identified by researchers: Broca's, Conduction and Anomic. A random sample of 22 patients with aphasia was selected and the type of aphasia was determined. The following results were obtained, there were 5 with Broca's, 7 with Conduction, and 10 with Anomic aphasia.
We need two columns in our spreadsheet to enter this table, one for the type of aphasia and one for the number of subjects with that type. To add columns to a spreadsheet simply double click to the right of the first column. Each time you double click to the right of the rightmost column another column will be added. Here we only need one additional column so we will double click once to the right of the first column. The first variable, aphasia type, is categorical/nominal/qualitative and JMP will automatically make this change when you enter the Broca's in the first field. You can change the name of the column from Column 1 to Aphasia Type by double-clicking at the top of the column. This will open the column info box where we can change the column name field to Aphasia Type. Other information in the column info box is the data type, how the variable will be used in statistical models, and the field width. Additional rows of data are created each time the Enter key is pressed.

For the second column all that is required after entering the frequencies is a name change. This can be done using the process described above, or by simple clicking on the current column name, Column 2, and changing the name to # of Subjects. These counts are actually frequencies and we wish the computer to interpret them as such. To do this we will use the role assignment menu to change this column’s role to that of a frequency count. The role assignment menu is accessed by right-clicking at the top of the column and choosing Freq from the Preselect Role pull-out menu as shown below.

When you are finished your spreadsheet should look like:

We can now save the data spreadsheet by selecting File > Save … JMP data files will always have a .JMP file extension.

The other approach for entering these data, which is probably more standard, is to have separate row for each subject in the study. For this simple study we would have a single column identifying the type of aphasia the subject has and 22 rows, one for each subject.
The resulting spreadsheet would look like this.

Regardless of which data entry approach is used the remainder of this tutorial applies.

A Preliminary Look at Graphical Methods for Categorical/Qualitative Data
Mosaic Plots and Frequency Tables
To obtain a mosaic plot and frequency distribution table for these data select Distribution from the Analyze pull down menu and place Aphasia Type in the right hand box by double clicking on it. Below is the resulting bar graph and mosaic plot for these data.

A relative frequency axis has been added to the bar graph by selecting that option from the Histogram Options pull-out menu. To access this menu click on the red down arrow to the left of the variable name, in this case Aphasia Type.


Below is the resulting frequency table for these data:

The Count column contains the frequency and the Prob column contains the relative frequency.

Bar Graphs and Pie Charts
Select Chart from the Graph main menu. FIRST (i.e. before clicking on anything else) select % of Total from the Statistics pull-down menu. Next place Aphasia Type in the X, Level box and finally click OK.The resulting bar graph is shown below.

To obtain a pie chart rather than the default bar graph select the Pie option from the Chart pull-down menu.


Getting Output
To print any graphic or table in JMP simply select Print from the File pull-down menu and it will print to your default printer preference.
A better approach to use in preparation of homework assignments is to copy and paste relevant output into Microsoft Word and then type your summaries and question answers next to the relevant output. To do this in simply select Edit > Copywith the output window highlighted and then go into Word and select Edit > Paste. Here is what the results of performing this process for the bar graph and frequency table should look like:

Distributions

Aphasia Type

Frequencies

Level / Count / Prob
Anomic / 10 / 0.45455
Broca's / 5 / 0.22727
Conduction / 7 / 0.31818
Total / 22 / 1.00000

You can now answer questions and summarize the results of your analysis.

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