Previous applications of Genetic Programming (GP) have been restricted to searching for algebraic approximations mapping the design parameters (e.g. geometrical parameters) to a single design objective (e.g. weight). In addition, these algebraic expressions tend to be highly complex. By adding a simple extension to the GP technique, a powerful design data analysis tool is developed. This paper significantly extends the analysis capabilities of GP by searching for multiple simple models within a single population by splitting the population into multiple islands according to the design variables used by individual members. Where members from different islands `cooperate', simple design models can be extracted from this cooperation. This...