Proper analysis of washability data can lead to the development of a maximum yield coal preparation plant flow sheet. Simulations, as simple as spreadsheet mass and water balancing, are important in examining yield maximization and middlings liberation. Key to such attribute tracking flow sheet simulations is the distribution model, expressing the probability of a species reporting to the product stream. There are many such equations proposed in the literature. This paper examines a functional form that can represent or fit most of the proposed distribution functions. Such a general function is very convenient in a general simulator, because the user need only define the relevant parameters instead of the appropriate equation and parameters.