The IFS was set up to help policy-makers, economists and members of the general public understand economic policy and its effects, for example how a national minimum wage would affect incomes across the UK population, and whether it would really be the best way to make poor people better off. A lot of this involves running economic models: simulation programs with which economists can change properties of a simulated economy and see how doing so would affect the public. One such program, developed at the IFS and used extensively in its research, is Taxben [Giles and McRae 1995], which allows its user to alter Income Tax rates and thresholds, National Insurance bands, and other properties of the tax and benefit system, and which then predicts how these changes will affect the finances of various segments of the population.
Given the IFS' mandate to improve public understanding of financial policies, the Web was an obvious medium to experiment with. The IFS set up a Web site in 1994, with the intention of making all its research papers and other publications available. In late 1995, I and Graham Stark, a full-time IFS staff member , took the next step, by designing an interactive Web interface to two models, Be Your Own Chancellor and Budget95. The first allowed users to play at being Chancellor of the Exchequer and see how their policies would affect various types of family. The second allowed its users to see how the Budget would alter their own financial circumstances. They are both still running --- Budget95 is now Budget96, and will be updated again for Labour's first Budget --- and can be accessed via the IFS home page, whose URL is given in the bibliography.
Both programs are clearly of interest to the general public. We realised that by making the analysis and reporting more detailed, we could build educational applications that would help economics undergraduates and A-level students. Soon after starting, it became evident that such applications can become very big, with numerous different forms to fill in (for Income Tax, VAT and other indirect taxes, National Insurance and so on) and numerous ways to give output (as graphs, as tables, etc). In addition, we had to cater for adminstrative needs such as allowing users to store their data on our server: this meant providing forms via which students could register a username, save data submitted from forms and delete unwanted files, and so on.