The motivation for this work is derived from the current interest in speeding up development schedules. A key implication of the shift to more rapid development methods is the growing emphasis on fixed time and fixed effort delivered during such projects. However, there appears to be little work that addresses the impacts of dealing with bound effort levels. The result of binding time and effort is to deprive project managers of the normal parameters that are used in trade-offs. The paper attempts to introduce a quantitative analytical framework for modelling effort-boxed development in order to uncover the effects on the overall development effort and the potential leverage that can be derived from incremental delivery in such projects. Models that predict product size as an exponential function of the development effort are used in the paper to explore the relationships between effort and the number of increments, thereby providing new insights into the economic impact of incremental approaches to effort-boxed software projects.