Concept: Declaration

The reason there are no values yet in the variable examples given above is because the examples are only what we call Variable Declarations. As we mentioned in the previous section, a variable declaration is the act of defining a variable, i.e. giving it its name, and the other properties required, but not its value. The value is assigned when processing takes place. We’ll look at the different types of processing after the lessons on declarations.

There are two kinds of declaration in TAO, one for each type of variable: Response Declarations and Outcome Declarations.

Response Declaration

The TAO Glossary defines Response Declaration as "A declaration of the contents of the Response Variable attached to an item. The Response Declaration defines characteristics of the Response Variable such as its name, type, and cardinality. It can also define properties relating to the scoring method which is to be applied to process the response, such as Correct response and Score map".

In other words, the Response Declaration is used to provide information about the expected form of the response(s) to a particular item. In the lesson Response Variable above, you can see that there is a feature 'Correct Response' in the variable, which has the value 'Naypyitaw'. This is the declaration of the correct response to the item.

Note: The other characteristics pertaining to the response (such as type and cardinality) are not important for our purposes here, so we won’t discuss them further.

Outcome Declaration

The TAO Glossary defines Outcome Declaration as "A declaration of the contents of the Outcome Variable attached to an item or test. An Outcome Declaration defines the characteristics of the Outcome Variable, such as its name, type, cardinality. It can also define properties relating to the scoring method which is to be applied to process the input".

The term Outcome Declaration is likely to be a relatively opaque expression for end users of TAO. Basically, Outcome Declarations are used to declare some aspect of the nature of the outcome which is being computed. Because this can relate to the scoring method used to work out the score of either an item or a test (i.e. it can be used to declare the scoring instructions, or criteria), it is sometimes used synonymously with ‘scoring criteria’, though this is only one aspect of it.

Note: Again, other properties can be declared which are not important for our purposes here, so we won’t discuss them further.

In the next lessons we’ll look at the way the declarations are used to compute the missing values for the variables. This takes place during Processing.