Modeling and Multivariate Methods - SAS

432 Performing Choice Modeling Chapter 16
Transforming Data
Figure 16.39 Partial Daganzo Travel Time Table for Three Alternatives
Each choice number listed must first be converted to one of the travel mode names. This transformation is
easily done by using the Choose function in the formula editor, as follows.
• Create a new column labeled Choice Mode. Specify the modeling type as Nominal. Right-click on the
Choice Mode column and select Formula.
• Click on Conditional under the Functions (grouped) command, select Choose, and press the comma
key twice to obtain additional arguments for the function.
• Click on Choice for the Choose expression (expr), and double click on each clause entry box to enter
“Subway”,” Bus”, and “Car” (with the quotation marks) as shown in Figure 16.40.
Figure 16.40 Choose Function for Choice Mode Column of Daganzo Data
The choice response is now in the correct format. Since each row contains a choice made by each subject,
another column containing a sequence of numbers should be created to identify the subjects. This can be
done by creating a column with the Subject label. Then, enter a 1 in the first row of the column, a 2 in the
second row of the column. Finally, highlight the first and second rows of the column, right click, and select
Fill > Continue sequence to end of table. A partial listing of the modified table is shown in Figure 16.41.
Figure 16.41 Daganzo Data with New Choice Mode and Subject Columns
In order to construct the Profile data, each alternative needs to be expressed in a separate row.