TABLE OF CONTENTS If we agree with the rule of left-to-right consistency, we are faced with a number of problems where it would seem that this is going to be a very difficult rule to comply with. In this section we will consider a number of techniques to solve this problem.
This is one of the thorniest of all modelling issues: how do we set up a model so that we can report either quarterly or annual results (or monthly to quarterly, etc.)? A basic modelling rule is that the model is set up using the smallest time units required if there is a requirement to report monthly then the whole model is set up at this level. This in itself is problematic, because with some types of analysis there may be more months in the forecast period than columns in Excel. The usual solutions tend to be a bit messy: the annual total formulae are interposed amongst the quarterly figures, and by judicial use of hidden columns we can laboriously convert from one time period to the other.
The immediate problem with this type of solution is first it requires a lot of effort (which usually ends up being macro-driven) and second, that it drives a coach and horses through the principle of left-to-right consistency. If any formula needs to be amended or updated, it is no longer a question of simply copying...
