Читать книгу See-Through Modelling - Dominic Robertson - Страница 36

Model flow is defined as the logical direction of information in the model. In much the same way as for that of a book where the reader will read from top to bottom and left to right this is also the model flow across and within sheets.

Model flow is from top to bottom and left to right.

In practice this means that logic in the model will try to use information from above and behind it as far as is possible. This gives the modeller and the user a clear starting point for where to place information and how to perform calculations. Every now and then it is necessary to use information from ahead of the present calculations and I call these counter flows.

Model counter flow is any flow of information that travels against the model flow.

For example, when calculating the corporation tax in any period of the model it is necessary to start with the profit before tax line from the financial statements and possibly make some adjustments in order to derive taxable profit. The tax sheet normally resides just before the financial statements sheet since the results of the tax sheet are used in the financial statements, so the profit before tax line used in the tax sheet is defined as a counter flow.

The number of counter flows should be kept to a minimum in order to preserve the conventions and maintain the integrity of the model.

Examples of unavoidable counter flows include:

 profit before tax (PBT) in the corporation tax calculation

 using beginning balances to calculate interest on a loan

 cash available subtotals from the financial statements are used throughout the model to allocate cash down through the cash flow waterfall.