Model Browser User's Guide

Response Surface View

You can change the view using the View menu or by clicking the buttons of the toolbar. The next view along the toolbar shows the model surface in a variety of ways.

The default view is a 3-D plot of the model surface. This model has four dependent factors; you can see these in the controls at the top left and in the menus below the plot.

You use the drop-down menus to select the input factors for the plot. The unselected input factors are held constant and you can change their values using the controls at the top left of the view (either by clicking the arrow buttons or by typing directly in the edit box).

Display using (SPK - datum) -- If a datum model is being displayed, this check box appears. The datum variable here is spark angle, SPK. When you select this box, the model is displayed in terms of spark angle relative to the datum. The appropriate local variable name appears here. See Datum Models.

Display Type -- Changes the model plot. Display options are available for some of these views and are described under the relevant view. The choices are as follows:

• A table showing the model evaluated at a series of input factor values.
• A 2-D plot against one input factor.
• A 2-D plot with several lines on it (called a multiline plot); this shows variation against two input factors.
• A contour plot.

• The Contours... button opens the Contour Values dialog. Here you can set the number, position, and coloring of contour lines.

  Fill Contour colors each space between contours a different color.

  Contour Labels toggles the contour value numbers on and off. Without labels a color bar is shown to give you a scale.

  Auto (the default) automatically generates contours across the model range.

  N Contour Lines opens an edit box where you can enter any number of contour lines you want.

  Specify values opens an edit box where you can enter the start and end values where you want contour lines to appear, separated by a colon. For example, entering 5:15 gives you 10 contour lines from 5 to 15. You can also enter the interval between the start and end values; for example 1:100:600 gives you contour lines between 1 and 600 at intervals of 100.

• A surface (shown above).

• Prediction error shading -- Colors the surface in terms of the prediction error (sqrt(Prediction Error Variance)) of the model at each point. A color bar appears, to show the value associated with each color.

Note    For datum models, Prediction Error shading is only available when the Display using (local variable - datum) check box is not selected.

• P. E. Threshold -- To see good color contrast in the range of PE of interest, you can set the upper limit of the coloring range. All values above this threshold are colored as maximum P.E.

• A movie: this is a sequence of surfaces as a third input factor's value changes.
• Replay replays the movie.
• Frame/sec selects the speed of movie replay.
• The number of frames in the movie is defined by the number of points in the input factor control (in the array at the top left) that corresponds to the time factor below the plot.

Export allows the currently displayed model surface to be saved to a MAT file or to the MATLAB workspace.

Predicted/Observed View

Likelihood View