A perennial problem of any organization which is involved in systems work of a changing nature is the need for the organization itself to change as i… - Harold Chestnut

Included in the problems of systems engineering are those of complexity and of choice. Of all the available facts about a system or the needs for a system, which are of most significance for the present circumstances and for their probable future course? How much information is needed and how should it be used to make a satisfactory decision, considering the time and resources available and the purpose to which these data are to be applied? Since most of the means of understanding which we as individuals use, or which are used by the automatic decision-making processes which we employ, are serial processes, we are continually faced with choices of how to divide the jobs to be done and to select an order or an arrangement for systematically handling the abundance of data which are available.

Each system is unique. However, by capitalizing on similarities we can reduce the time, effort, and cost for some or all of them, and thus the quest for formalized design methods becomes more attractive.

Models are used essentially for evaluation and prediction purposes as well as for the analysis and study of the different parts of the system so that the systems engineer or designer may arrive at sound engineering decisions regarding the system design.