The resource decisions in software project using cost models do not satisfy managerial decision, as it does not support trade-off analysis among resources. A Bayesian net approach enables this analysis; however, it requires discretization of parameter values and thus sacrifices accuracy. Although narrow intervals can alleviate this problem, the number of states grows quickly with the demanded accuracy. The Bayesian approach also requires pre-setting of the measurement scale, which may not be applicable to all users. In this paper, we propose using a risk assessment model to aid software resource decisions. The methodology employs a continuous function that captures key parameters of software development, such as development time, staff productivity, requirement volatility and software complexity. Using the model, users can perform trade-off analysis among various resource allocations and outcomes. We also propose integrating this model with optimization to solve complicated problems, which can be accomplished straightforwardly with the proposed methodology.