The choice of model should depend on the ultimate need that the forecasting model will fulfill, the resources available for the development of the model, and the availability and quality of data. [...] It will outline the model and describe the steps involved in its development, the role of occupational and industry categories, the required components and inputs, and the forecasting techniques. [...] Occupational Forecasting and the Labour Market A. A Changing Economy and Labour Market There are a number of factors affecting the supply and demand of labour. [...] In the context of occupational forecasting, however, or at least for the purpose of this report, occupational demand and supply are flow variables, in that they refer to changes in the level or stock of required or available workers. [...] Similar to the concept of separations is the concept of replacement demand which refers to the number of workers required to replace the workers leaving an occupation.