Actual implementation of the VaR system will be a different process depending on whether you install vendor software or internally developed your own system. However, since most implementations combine some vendor software and some internally developed software, your own implementation is likely to blend the two processes.
12.6.1 Internally Developed Software
The first step in internally developing VaR software is for quantitative finance professionals to work with IT professionals to develop a design document. This will be the primary point of communication between business and IT professionals on the design team. The business professionals will provide the detailed know-how on the algorithms and processes required, while the IT professionals will provide expertise on how to best partition the technical solution.
The purpose of the document is to detail all inputs, mathematical formulas and outputs for the VaR system. The document should be expressed in non-technical language to the extent possible, so as to be accessible to both finance and IT professionals. Authors should draw on both the requirements document, which should already exist, and this book, which provides detailed information on the analytics one might incorporate into a VaR system. If authors adopt the terminology and notation of this book, then the book can serve as a reference to support the design document.
If use cases are employed for the requirements process, the design documentation will be driven from the use cases. The design process will consist of expanding each use case with design details.
After this design document is finished, the authors will need to be available on an ongoing basis to answer the inevitable questions that arise during the implementation. You can expect that the requirements and design of the system will undergo revisions throughout the implementation process. Strive to make the requirements document complete, but plan for the “80-20 rule”—80% of the requirements will be defined in the requirements phase of the project, while 20% of the requirements will be discovered during the design and implementation process. For this reason, it is critical that the business experts participate in frequent reviews throughout all phases of development.
12.6.2 Agile Software Development Methods
There are a number of agile software development methods (e.g., Scrum, Extreme Programming (XP), Test-Driven Development) that have become popular for developing complex systems such VaR solutions. These methods can be effective for VaR development because they employ frequent, focused software releases to deliver the solution incrementally.
The primary benefit to an agile approach is the immediate feedback and business value of each release. By delivering smaller software releases sooner, the firm realizes business value more quickly and also is able to adjust for missing/incorrect software requirements earlier rather than later in the development process.
There are only certain contexts where agile methods can be used effectively, so development teams pick and choose various aspects of these methodologies for development. An experienced team is needed for any of these methods, so you will need to consult your IT team to determine if agile methods make sense for your implementation.
12.6.3 Vendor Software
Vendors will generally take responsibility for implementing their own software, but your implementation team should be an active participant in the process. Vendor software is often configurable in different ways, and team members should be active in deciding how their system should be configured. They should receive training in the vendor software before it is implemented, so they are fully versed in its features and configuration options.