Model Browser User's Guide

Local Level

When you select a local node (with the  icon) in the model tree, this view appears.

Note that after the two-stage model is calculated the local node icon changes to a two-stage icon (  ) to reflect this. See the model tree for clarification. The response node also has a two-stage icon, but produces the response level view instead.

The following example shows a local model of torque/spark curves.

See Local Level: Toolbar and Local Level: Menus for details on these controls.

The default view is the Model tab, described below. See also Data Tab.

Upper scatter plots are replaced by an icon if you resize the Browser too small.

Local Special Plots

The lower plots are referred to as special plots as they can be different for different models.

The lower plot at the local level shows the local model fit to the data for the current test only, with the datum point if there is a datum model. If there are multiple inputs to the local model, a predicted/observed plot is displayed. In this case to examine the model surface in more detail you can use Model -> Evaluate. See Model Evaluation Window.

You can scroll through all the local models by using the up/down test buttons, type directly in the edit box, or go directly to test numbers by clicking Select Test.

To examine the local fit in more detail, double-click the arrows (indicated in the preceding figure) to hide the scatter plot and expand the lower plot. You can zoom in on parts of the plot by Shift-click-dragging or middle-click-dragging on the place of interest on the plot. Return to full size by double-clicking.

You can change the lower plot from the Local Response to a Normal Plot by using the drop-down menu at the top of the plot.

Above are the right-click context menus for both plots. On both plots you can manipulate outliers with all the same commands available in the Outliers menu. See Outliers Menu (Local Level) for details.

On both plots the Print to Figure command opens a MATLAB figure plot showing the current plot. On the special plots you can switch the confidence intervals and legend on and off, and hide or show removed data.

Local Scatter Plots

The upper plots are referred to as scatter plots. They can show various scatter plots of statistics for assessing goodness-of-fit for the current local model shown.

The statistics available for plotting are model dependent.

The preceding is an example drop-down menu on the scatter plot for changing x and y factors. In this case spark is the local input factor and torque is the response. The local inputs, the response, and the predicted response are always available in these menus. The observation number is also always available.

The other options are statistics that are model dependent, and can include residuals, weighted residuals, studentized residuals, and leverage.

Diagnostic Statistics Pane

The Diagnostic Statistics pane drop-down menu is shown, where you can select the information to be displayed in the pane. If there is not enough room there are scroll bars.

• Local Parameters -- Shows the values and standard errors of the parameters in the local model for the current test selected.
• Local Correlations -- Shows a table of the correlations between the parameters.
• Response Features -- Shows the values and standard errors of the response features defined for this local model, from the current test (often some or all of them are the same as the parameters; others are derived from the parameters).
• Global Variables -- Shows the values and standard errors of the global variables at the position of the current test.
• Local Diagnostics -- S.i. (the standard error for the current test), number of observations, degrees of freedom on the error, R squared, Cond(J or Sigma): the condition index for the Jacobian matrix or the covariance matrix.
• Global Covariance -- For MLE models, shows a covariance matrix for the response features at the global level.

For information on the Pooled Statistics, see Definitions.

Response Features List Pane

See the Test Plans List Pane for information on the lower pane, which here contains a list of response features (with New, Delete, and Select buttons). The contents of this pane change in different views; it always contains the child nodes of the node selected in the model tree.

Here is a list of all the response features calculated for the local model. A two-stage model using the local and global models is formed by using Select. Click the Select button here to enter the Model Selection window. This step is required before two-stage models can be calculated.

Test Notes Pane

You can use the Test Notes pane to record information on particular tests. Each test has its own notes pane. Data points with notes recorded against them are colored in the global model plots. You choose the color using the Test Number Color button in the Test Notes pane.

New Response Models

Local Level: Toolbar