Sensitivity Analysis

COPASI enables you to calculate the sensitivities of a model with respect to various parameters. In general, a sensitivity measures how much a specific observable (that is, any value produced from numerical analysis of the model) changes in response to variations in a given parameter.

You can compute arrays of sensitivities for lists of observables with respect to lists of parameters. All settings for sensitivity analysis are available in the Tasks → Sensitivities section.

For example, suppose your model reaches a steady state. You may want to see how the steady-state concentrations are affected by different kinetic parameters. To perform this analysis in COPASI, you might choose the following settings:

To perform a typical sensitivity analysis in COPASI, select the following options:

• Subtask: Choose Steady State. This setting indicates that you are interested in the sensitivities of steady state calculation results.
• Function: Select Non-Constant Concentration of Species. The “Function” specifies the observables—here, the steady state concentrations for which you want to determine sensitivities.
• Variable: Set this to Local Parameter Values. Local parameters refer to kinetic parameters that are directly specified for the model’s reactions.

Once these options are set, click the Run button to start the calculation.

The results of the sensitivity analysis are presented as color-coded tables of numbers. These tables make it easy to visually interpret how each observable responds to changes in the selected parameters.