Sketchables

A sketchable graph contains both the plot of a model variable and a sketchable plot that the user can update. Sketchables are very useful for putting in expectations about results and then simulating to compare the actual outcomes of the simulation to those expectations.

To define a sketchable graph

A sketchable graph allows model users to "sketch out" their goal or expectation of the performance for a single variable against the variable's actual performance over a simulation run.

When you create a sketchable graph, the graph displays two curves: the actual performance of the variable (shown in the following example as a red curve), along with the user-created sketch of the curve for that variable (shown as an orange curve).

  1. Open the Graph Properties Panel for the graph pad you want to edit. (Click on the graph pad in Edit mode, or double click in Explore or Experiment mode).
  2. Add the model variable you want to graph (Population[Deer] in the above example) to the graph. You can add more than one variable, though typically adding only one works best.
  3. At the bottom of the panel, add a variable defined as a graphical function over time to Sketchable Options. This is the variable the user will sketch (it's My Guess in the above example). Note that this variable will always be a converter, even if the model variable from step 2 is a stock or a flow.
  4. Be sure to uncheck the Multiscale option under Left Y Axis.

You and your model users can now create the sketch by clicking inside the graph and dragging, to draw the desired curve. When the model simulation runs, the actual curve appears on that graph along with the sketch.

Using a Sketchable for Input

It's not necessary to include a variable in a sketchable graph. You can include only the graphical function being sketched; in this way, the sketchable becomes an input device analogous to the knobs that are displayed in Explore mode. As you change the graph, the model will be simulated each time you release the mouse button, and you can instantly see the results of the change made.