How to build a custom variable definition file

Like macros and custom setup files, custom variable files are editable plain text (ASCII) files consisting of combinations of statements which define the variables. The general structure of a variable definition file may look like this:

comment or title

[variables]
'comment
statement 'comment
statement 'comment
[end]

Steps to create a custom variable definition file ...

1. Create a blank document using Windows™ NotePad or any word processing program that can save documents as plain text.
2. At the beginning of a new line, type [variables] to indicate the beginning of the variable definition section.
3. Build a data matrix and a corresponding selection mask using an appropriate combination of the following statements:
   • Compare statement
   • Matrix statement
   • Include statement
   • Exclude statement
   • Transform statement.
4. Based on a data matrix, you can either create profile variables, trial variables, case variables, surface variables, or bullets. Note that mixing different variable types in the same file is no allowed. If you wish, you can apply conditional trial discarding to any type of variable. All this is accomplished by appropriate combinations of the following statements:
   • Collapse statement
   • Surface statement
   • Window statement
   • Extract statement
   • Collect statement
   • Discard statement
   • Verify statement
   • Tabulate statement
   • Bullets statement.
5. Repeat steps 3 and 4 until you have defined all variables of your analysis. When done, type [end] at the beginning of a new line to indicate the end of the variable definition section.
6. Above [variables] and below [end] you may enter any free text or commentary.
7. Save the file as plain text and give it the extension .VDF. Use the Analyze Case Document command to apply the file to all trials or to selections of trials in case documents.

Include files...

The engine that processes variable definition files has a preprocessor which replaces directives of the form {{file_path}} or {{file_name}} by the content of the specified file, e.g. a group of statements that are used in several variable definition files. You may either specify a complete file path or only a file name. In the latter case, the file is expected in the same directory as the containing VDF. Nesting of file inclusion directives is possible.

Additional information...

• Managing custom variable definition files provides general information on the management of custom variable definition files.
• The Flowchart of advanced data analysis gives a synopsis of data and variable types.
• How to define variable blocks explains how to define case variables more efficiently by grouping them into variable blocks.
• Using the Memory statement you can build collections of data matrices for later reuse in other variables.
• There is a list of all available variable definition statements.
• See Analyze Case Document command for basic information on that command.