Validation is a step in the simulation procedure. Some assurance is needed that the results of the experiment will be realistic. This assurance requires validation of the model --often using historical data. If the model gives results equivalent to what actually happened, the model is historically valid. There is still some risk, however, that changes could make the model invalid for the future.

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A fundamental characteristic of databases is that applications are independent of the database structure; when writing programs or designing applications to use the database. Only the name of the desired item is necessary. Programs can be developed for the user's specific needs without concern for data capture problems. Reference can be made to the items using the data manipulation language, after which the DBMS takes care of locating and retrieving the desired items. The physical or logical structure of the database can be completely altered without having to change any of the programs using the data items, only the schema requires alteration.