Lesson 2: Scenario Analysis

The Scenario Analysis menu options allow users to change parameters (and therefore relationships) and selected initial conditions in the model in order to create different scenarios and analyze them. This section of the Help Menu will guide you through the process of changing these relationships and displaying your results.

Quick Scenario Analysis with Tree

This sub-option can be reached from the Scenario Analysis option on the Main Menu of IFs. The Quick Scenario Analysis with Tree allows users to change parameters and initial conditions with high levels of flexibility. Learn more about the Quick Scenario Analysis with Tree topic.

Explore and test your knowledge:

1. How can you find a parameter you want to change? Find a multiplier that would allow you to increase the total fertility rate of Nigeria by 10 percent relative to the Base Case.
2. Change the parameter you found in question 1 so that the fertility rate is increased by 10 percent relative to the Base Case over a period of 20 years.
3. Run the model for 20 years so that the parameter change in question 2 is used to recompute all variables in the model including the fertility rate of Nigeria. Use the Flexible Displays form to see that the change in fertility was implemented and see what the results are for Nigerian population and GDP per capita (relative to the Base Case).
4. Save the parameter change you made in question 2 in a .sce (scenario) file. Close IFs, re-open it, and retrieve the .sce file into the Self-Managed display form.

Change Selected Functions

This sub-option can be reached from the Scenario Analysis option on the Main Menu of IFs. The Change Selected Functions allows users to alter bivariate functions or multivariate functions. Learn more about the Change Selected Functions topic.

Explore and test your knowledge:

1. What is the difference between bivariate functions and multivariate functions?
2. What is the difference between table functions and analytic functions within the bivariate function category?
3. How do you change the intercept value for a bivariate function? For a multivariate function?

Running Working Scenario

The Run sub-option can be reached from the Scenario Analysis option on the Main Menu, or from within the Quick Scenario Analysis with Tree option. This feature of IFs allows users to run the working file where they have made scenario changes. Learn more about the Running the Working Scenario topic.

Explore and test your knowledge:

1. What is the difference between the Working File and the IFs Base Case file?
2. What piece of information must be specified on the Running Working Scenario form?
3. After you have completed a new run of the Working File, how would you compare the forecasts of that with those of the Base Case?

Reload the Base

This Scenario Analysis option is used to 'reset' the model to its original state after using the scenario tree to build a scenario or after loading pre-existing parameter changes. Learn more about Reloading the Base.

Explore and test your knowledge:

1. What changes are made to the Working File when the model is run?
2. What changes may occur when the base is reloaded?