Читать книгу See-Through Modelling - Dominic Robertson - Страница 85

The design of a model is about the structure, organisation and choice of logic. So model design is also about the choice of formulae. For a project finance company in operations there is limited design left to do given the sheer quantity of projects out in the market. In other words, there is a clear template that can be used.

However, there will always be occasions when some further design is necessary to overcome particular difficulties. These might arise from projects with more complicated operations, such as waste water projects. Or they might arise from more complicated finances, with more tranches of junior debt, such as mezzanine finance. Essentially the model is a pragmatic expression of a series of contracts between various parties and the project company. So design also means the nitty-gritty logic that describes these contracts.

There is good design and bad design.

Good design:

 achieves the objectives in an elegant and transparent solution

 knows its limitations – it is not the intention to build a model that can withstand a 100-year storm

 flags errors and requires further design later as required

 employs clear organisation and structure

 has no duplication or repetition

 minimises logical counter flows

 minimises the number of reports

 understands the importance of model maintenance for the success of a model

 above all, is simple.

Bad design:

 is over-complicated logic

 is massive formulae

 is changing timelines on the same sheet

 is disorganised and has a lack of structure

 is repetitive and duplicative

 has no respect for hierarchy

 creates endless rehashed versions of the financial statements that will require constant maintenance, and

 is the use of un-auditable formulae like OFFSET.