Scale Selection Window

The Scale Selection Window can be activated from the Model Page while positioned on some attribute. Using this window, it is possible to select some scale and associate it with the selected attribute. In principle, all scales, which are currently defined in the model, are available, but subject to restrictions explained below.

The following screenshots illustrate two examples of scale selection using the Employee Selection model. In both cases, the scales currently assigned to the selected attribute are displayed at the top of the window.

Selecting Scales of a Newly Created Attribute

In this case, Test is a newly created attribute and its scale is currently undefined. Any discrete scale (marked ), already defined in the model, can thus be assigned to the attribute. Since Test is also the only child of its parent attribute, any continuous scale () can be used, too.

Selecting Scales of an Attribute With a Defined Scale

In this case, not all available scales can be assigned to the existing attribute Comm, whose scale contains four values, as indicated at the top of the dialogue. Only other already defined scales that also contain four values can be assigned to Comm.

Predefined Scales

DEXiWin provides several predefined, generally applicable value scales. These can be added to the selectable list by checking the “Show predefined scales”.

Remarks

The assignment of scales to attributes is subject to some restrictions.

The main requirement is that the assignment must not affect any functions that might be already defined in the neighborhood of the attribute. Another restriction is that discretization functions can have exactly one continuous child attribute. This leads to the following rules:

• Any qualitative scale can be assigned to any attribute whose scale is currently undefined.

• Some qualitative scale can be assigned to an attribute with already defined qualitative scale only if both scales have the same number of values.

• Any continuous scale can be assigned to a basic attribute that is a single parent of its parent attribute, provided that its scale is undefined or continuous, and the parent’s function is undefined or of discretization type.

In the above screenshots, notice the checkbox “Default scale for new attributes”. Checking this box tells DEXiWin to automatically associate the selected scale with all newly created attributes. This speeds up the creation of attributes and avoids defining a scale explicitly for each new attribute. Of course, this functionality is useful only when the majority of scales in the model are of the same type.