In addition to changing the shape of inputs it is possible to freeze levels at their initial value. To do this check the Freeze Levels at initial values checkbox.
You can then override one or more variables to study the local response of a set of equations to their inputs. Typically, one of the inputs would be specified as a ramp over a useful range and the sensitivities to different constant tested.
Consider the equation
effect price demand = (price/average price)^(-elasticity)
If we make changes to elasticity and run the whole model price and average price will both move and it will be difficult to see the effect of price on for different prices. However by overriding the behavior of price to be a ramp, and freezing the levels we have isolated the structure so that we can study its local behavior. You can use Strip Graphs to visualize these relationships.
NOTE Freezing a Level clamps the value of the Level itself; the flows into and out of it are untouched and keep their computed values. A frozen Level can therefore display a nonzero net flow — the suppressed change is not apportioned back to the flows.
