Split Role Modelling

The principle behind "split role" modelling states that there are two distinct roles involved in developing a spreadsheet model: a conceptual modeller and a spreadsheet engineer. Allowing the same person to take on both roles causes a conflict that affects both the efficiency and quality of the spreadsheet.

• The conceptual modeller is a business expert who understands the terrain that the model will map.
• The spreadsheet engineer is a cartographer who captures the terrain detail and creates a scaled map.

Split role modelling, by Professor Thomas Grossman, University of San Francisco, School of Business Studies

When a conceptual modeller begins to describe the terrain to the cartographer, it can help if he makes a few spreadsheet sketches to give an idea of the lay of the land. The spreadsheet engineer refers to these sketches when building the map, but the final spreadsheet will be better and more detailed than the original sketch.

To use a different metaphor, the conceptual modeller is the end user who wants a piece of software and the spreadsheet engineer is the developer who codes it. The way split role modelling works is similar to agile software development methods: a small team of highly skilled professionals work closely with the end user to produce a product that meets specific requirements. The programmers have skills that the end user lacks and in turn the end user has business insight that the programmers lack. Together they create something that brings all their knowledge into one product.

Open channels of communications and short development iterations are crucial to the approach. This ensures that the end product remains in focus throughout the development process.