To view the results of an optimisation run, choose File » Load results. This will load the Results dialog where you can view the results in various graphical formats.
Optimisation run results are compared to the Pareto Front. The Pareto Front is the set of solutions which have differing performance on each of the objectives. A solution is not on the Pareto Front if there is an alternative that is better on at-least one of the objectives but no worse on any objectives. In this case the solution is discarded as the alternative is clearly preferable. If the Pareto Front solutions are not changing, the optimiser may have satisfactorily completed its multi-objective search.
Hypervolume plot
During the optimisation run (when using the interface), after more than a generation is complete, you will be able to view the hypervolume plot – an indication of how the Pareto Front (selection of optimal results) is converging. The hypervolume provides an indication of the convergence of the model results towards the Pareto Front. The hypervolume is calculated based on the distance between a maximum non-optimal solution and the modelled results. In effect, the larger the hypervolume, the closer the results are towards reaching the Pareto optimal solution. The hypervolume provides an indication of the convergence of the model results towards the Pareto Front. It is calculated based on the distance between a maximum non-optimal solution and the modelled results. In effect, the larger the hypervolume, the closer the results are towards reaching the Pareto optimal solution.
Insight provides two plots of hypervolume when using the user interface (shown in Figure 1). The blue hypervolume plot is calculated whilst Insight is running, without knowing what the maximum non-optimal solution is (shown on the left of Figure 2). The red hypervolume plot is calculated at the end of the optimisation run, using the maximum non-optimal solution as reference. The hypervolume is a useful indication of how much the optimal solutions are changing – if the hypervolume plot is flattening out, this is a sign that more generations are unlikely to produce more optimal results.
Figure 1. Insight results, hypervolume plots
Two-dimensional graph
Click the 2D Graph tab at the top of the Results dialog to view two-dimensional scatterplots of the results (as shown in Figure 2). The drop-down menus for the x and y axes list all the objectives specified in the optimisation. To view the graph for a particular relationship, choose the relevant items from the drop-down menus and click Plot. The example shown in Figure 2 has three objectives defined: $reliabilityNeg, $unitcost and $Yieldneg. The points on the graph are forming the Pareto Front for this optimisation.
The Filter Properties dialog allows you to view the results in a specified range:
- Choose the type of plot (scattered or pareto) in the Plot Option drop-down menu;
- In the Selected Filter drop-down menu, choose the filter and click Edit Filter;
- This opens the Edit Filter dialog (shown in Figure 4) showing the entire range of values.
- You can change the filter's name using the Filter Title panel.
- Edit any value by double clicking on the cell you wish to change and enter the required value (in the Lower Filter or Upper Filter columns); and
- Click OK to save changes close the Edit Filter dialog or Cancel to quit without saving.