Introduction

See Quick Access for jumps to information on particular topics. The following section is an introduction to the basic ideas behind RunDynam and a broad overview for new users.

RunDynam allows to you to construct a base case and policy deviations from the base case with a dynamic model which has been implemented using GEMPACK. The model is solved on a year-to-year basis (that is, recursively) over a number of years, starting from initial data. For each subsequent year, the starting data is the updated data produced by the previous simulation.

As an example, the problem to be solved is to use a dynamic model to produce

•a base case (which may be a forecast) for a set of years in sequence, for example, for the years (2001, 2002,….2010)

•a deviation from the base case in response to some change in policy, again for a sequence of years, for example, the years (2004, 2005,…..2010).

The results that RunDynam produces are the simulation solutions for the base case for each of the years, for example (2001, 2002,,,,,2010) and the solutions for the policy for each of the policy years for example (2004, 2005,…2010). Other interesting results are the cumulative differences between the base case and the policy simulations.

A complete policy simulation consists of 2 or 3 multi-year runs, namely the Base run, the Rerun of the Base (if being done) and the Policy run.

Each of these multi-year runs consists of a sequence of linked annual simulations.

In the example above, the Base Case is the sequence of linked annual solutions for the years (2001, 2002,…2010). The Policy run is the sequence of linked annual simulations, with the additional policy shocks, for the years (2004, 2005,…2010).

For example, in a complete policy simulation, you could first carry out the Base Case run, then carry out the Policy run.

With some models it is customary to Rerun the Base Case before carrying out the policy deviation. In this case, you could first carry out the Base Case run, then the Rerun Base run and then the Policy run.

Carrying out a complete simulation can be controlled by the three buttons on the bottom left hand side of the screen marked Run Base Case, Rerun Base, Run Policy. (Alternatively, the individual annual simulations making up a complete policy simulation can be carried out in various orders.)

Before you start the simulation runs, you need to fill out the different pages of the RunDynam interface. This interface is called a tabbed notebook interface. The different Tabs just under the Menu bar at the top of the screen are: Introduction, Model/Data, SimOverview, Closure/Shock, Results and Other Files. To go from one page to the other, just click on the Tab.

On the Introduction page you will see the name of the program, its copyright and details about your RunDynam licence.

On the Model/Data page, you choose the dynamic model and any group of input data files for the model; these are the starting points for your base case.

On the Closure/Shocks page, you specify closures and shocks on text files, using the syntax required in GEMPACK Command files.

On the Sim Overview page, you set up the number of years in a complete policy simulation and you choose names for the output files from the base case and policy runs. You can choose among several methods to solve the model.

When you have run the simulations for the Base case, Rerun and Policy, on the Results page, you can view the results of the base case or policy deviation on the screen, or export them to other programs. You can view or copy either the initial model database or any of the updated data files produced during the base case or policy deviation.

To use RunDynam for the first time, see Getting Started. This example starts from a Zip Archive which can be used to load the ingredients of a complete policy simulation into the correct pages of RunDynam. This gives you an example to follow when you are setting up your own policy simulation. A Zip archive is a good way to save all the ingredients in a tidy package for later use or to give to other users. (Ingredients are all the files needed to run a complete policy simulation such as the model program files and first year data files, the closure and shock files and the simulation details on the different pages of the RunDynam interface which control the complete policy simulation.)

This Help file contains a large amount of detailed information. If printed as a normal A4 document, it would be about 100 pages long. We encourage you to use this Help file frequently. Click on Contents to see the list of topics covered or see Quick Access for jumps to information on particular topics.

If RunDynam gives you a message you are uncertain about and this message contains a Help button, click on that Help button since you will get context-sensitive help.

Although this Help file contains a lot of information, it is not easy to learn the important features of the software just from the Help file. You can get a very good introduction to the software and to dynamic modelling at one of the Dynamic CGE modelling courses, run by the Centre of Policy Studies-- see http://www.copsmodels.com/courses.htm.

URL of this topic: www.copsmodels.com/webhelp/rundynam/hc_first.htm

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