Model Browser User's Guide

Model Tree

The tree in the All Models pane displays the hierarchical structure of the models you have built. Views and functionality within the browser differ according to which node is selected.

The following is an example of a model tree.

The elements of the tree consist of the following:

1. Project node
2. Test plan node
3. Response node
4. Local node
5. Response feature nodes

Note    The selected node governs the model that is displayed in the various other panes of the browser and which menu items are available. The selected node governs the level displayed: project level, test plan level, and so on. The functionality of each level is described in the Help.

You can rename all nodes, as in Windows Explorer, by clicking again or by pressing F2 when a node is selected.

There is a context menu available. When you right-click any node in the model tree, you can choose to delete or rename that node, or create a new child node.

Tree Structure

The preceding example shows a more extensive model tree, with two two-stage models as child nodes of a single response model.

There can be many models within (or under, as child nodes in the tree) each response model node.

There can also be many different response nodes within a single test plan, and each project can contain several different test plans. However, there is only one project node in the tree at any time.

Note    You can only have one project open at any one time; if you open another, you are prompted to save or discard your current project.

Response features can themselves have child nodes -- several models can be tried at each response feature node and the best selected. There is an example showing this at the end of the section on Icons: Blue Backgrounds and Purple Worlds.

Icons: Curves, Worlds, and Houses

The icons are designed to give visual reminders of their function.

• Test plan icons have a tiny representation of the test plan diagram. You can see the one-stage and two-stage icons in the following example.
• Response features have global models fitted to them, so their icons show a curve over a globe.
• The local model icon shows a curve over a house.

  

• The response node (empty until a two-stage model is calculated) has an icon that combines the local and global motifs -- a curve over a house and a globe -- to symbolize the two-stage process.
• When a two-stage model has been calculated, the icon at the local node changes to show the combination of local and global motifs.

Icons: Blue Backgrounds and Purple Worlds

Icon changes convey information about modeling processes.

• When a model is selected as the best model, its icon changes color and gains a blue background, like the BSPLINE1 model in the preceding example.
• When the maximum likelihood estimate (MLE) is calculated and chosen as the best model, the associated model icon and all its child nodes (along with the plots of that model) become purple.

• You can see this in the preceding example: the B Spline model and all its response features have purple curves, globes, and house, indicating that they are MLE models. The Poly3 model and its children have blue curves and globes and a red house, indicating that they are univariate models.

• Observe the other difference between the B Spline and the Poly3 icons: the B Spline has a blue background. This indicates that this is selected as best model, and is used to calculate the two-stage model at the response node, so the response node is also purple. If an MLE model (with purple worlds) is selected as best model and is used to create the two-stage model, the response node always reflects this and is also purple.
• Notice also that the response features all have blue backgrounds. This shows they are selected as best and are all being used to calculate the two-stage model. In this case they are all needed. That is, a B Spline model needs six response features, and a Poly3 model requires four. If more response features are added, however, some combination must be selected as best, and the response features not in use do not have a blue background.

In the following example you can see child nodes of a response feature. You can try different models within a response feature, and you must select one of the attempts as best. In this example you can see that Cubic is selected as best, because it has a blue background, so it is the model being used for the Blow_2 response feature.

When a model is selected as best, it is copied up a level in the tree together with the outliers for that model fit.

When a new global or local model is created, the parent model and outliers are copied from the current level to the new child node. This gives a mechanism for copying outliers around the model tree.

A tree node is automatically selected as best if it is the only child, except two-stage models which are never automatically selected; you must use the Model Selection window.

If a best model node is changed the parent node loses best model status (but the automatic selection process will reselect that best model if it is the only child node).

Project Level: Menus

Test Plans