Would Results be the Same if You Ran All Jobs Again?

This sort of question is asked when you select either of the two items

Where To Start? Results Be the Same if Ran Again

Are Results Ok? Be the Same if Ran Again

under the Tasks menu.

These attempt to answer the question:

Suppose that you run everything now starting at the beginning of the Base. How far into each of the runs (Base, Rerun, Policy) can you be confident that you will be wasting your time, in the sense that the results you would generate will be no different from the results still available from previous runs?

A similar question is also being asked if you ask to start certain jobs and ask RunDynam to check if the prerequisites are ok. RunDynam then checks if you can be confident that you would be wasting your time if you run the prerequisite simulations you are not going to run in the sense that the results you would generate will be no different from the results still available from previous runs.

Suppose that you are told that you can be confident of the results from the Base up to year number 8 and that you can be confident of the results from the Rerun and Policy up to year number 6. Then, instead of running everything again, you might as well start from year number 9 of the Base and year number 7 of the Rerun and Policy.

Examples.

•Suppose that you run everything from scratch. Now suppose that you alter the name of the Policy Closure file (on the Closure/Shocks page) for year number 6 and then ask Are Results Still OK?. You will be told that all Base results are still ok but that the last results from the Rerun and Policy you can be confident of are those from the simulation for year number 5.

•Suppose that you run everything from scratch. Now suppose that you delete the Solution file from year number 5 of the Base and then ask Are Results Still OK?. You will be told that the last results from the Base, Rerun and Policy you can be confident of are those from the simulations for year number 4. [The Solution file for year number 5 of the Base is a vital input into the simulations for year number 5 for both the Rerun and Policy. Since it is missing, you cannot be confident

The results checked are

•the Solution, SLC and Log files from each simulation,

•the output data files (updated data and any files produced by Write statements) from each simulation,

•the spreadsheet files produced by the Spreadsheet jobs.

•The SOL Files used for Shocks during the Rerun and Policy (if option SOL files for Shocks is selected)

When you select Are Results Still OK?, you will be presented first with a form which asks you to indicate which of the above types of files you want the software to check. Then the software will only check the files you have indicated when answering the question Are Results Still OK?.

As you know, you are always aiming for a set of results that have been run in sequence. In preparing the answer for you, the software only looks at results which have been obtained in sequence. [Suppose, for example, that the last time you ran year number 5 of the Base was before the last time you ran year number 4 of the Base. Then the software will not tell you that you can be confident of the results from year number 5 of the Base. Nor will it tell you that you can be confident of the results from year number 5 of the Rerun or Policy since, if you redo year number 5 of the Base, you would also need to redo year number 5 of the Rerun and Policy in order to get them in sequence with the Base.]

In carrying out this check, the software makes the (hopefully reasonable) assumption that the results depend only on the complete set of inputs to the total process.

Even though you may carry out the whole run in several stages, you are aiming for results you can be confident are the same as those you would obtain if you run everything from scratch.

In preparing the answer for you, the software checks that all the inputs (as listed above) are the same as they were when you last ran the relevant simulations and spreadsheet jobs. It also checks that the output files from these jobs are still available and are the same as they were when you last ran the job.

Note that there is some slight possibility that files are different even when the software reports confidence that they are the same. So you can never be absolutely certain that the results are all ok unless you run them all from scratch.

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

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