Although a number of attempts have been made to apply the principles of systems theory to the business environment, there are major differences between scientific models and the business environment. Very often, the natural sciences deal with closed systems in which all the parameters are known, and each can be monitored and controlled. Admittedly, this is not always true; for example, in some ecological studies it may not be possible to identify all life forms that might possibly migrate into a system. By contrast, the business environment is essentially an open system in which it is very difficult to place a boundary round the environment and to identify the complete set of components within the system. Elements may come or go from the system and a researcher generally has no control over these elements in the way that a laboratory-based scientist could carry out controlled experiments.