Documenting and Approving the Data

When it is felt that all relevant information has been gathered and organized into a usable form, it is advisable to document the information in the form of data tables, relational diagrams and assumption lists. Sources of data should also be noted. This document should then be reviewed by others who are in a position to evaluate the validity of the data and approve the assumptions made. This document will be helpful later if you need to make modifications to the model or look at why the actual system ends up working differently than what was modeled.

In addition to including those factors to be used in the model, the data document should also include those factors deliberately excluded from the model because they are deemed to be either insignificant or irrelevant. If, for example, break times are not identified in the system description, a statement of explanation should be made explaining why. Stating why certain factors are being excluded from the system description will help resolve later concerns that may question why the factors were omitted.

Validating system data can be a time-consuming and difficult task, especially when many assumptions are made. In practice, data validation ends up being more of a consensus or agreement that is obtained confirming that the information is good enough for the purposes of the model. While this approved data document provides the basis for building the model, it often changes as model building and experimentation get under way.