The following principles must be kept in mind while formulating models.  PRINCIPLE OF SIMPLICITY Mathematicians are of the habit of making complex models whereas one should go in for simple model. It means model must be kept simple models.  UNDERSTAND THE PROBLEM, ONLY THEN APPLY THE APPROPRIATE TECHNIQUE If we do not understand the problem properly, we cannot apply the appropriate technique of operation research. For example, in case of allocation of scarce resources, the technique of LPP may be applied.

 IMPLEMENTATION Model must be validated before implementation otherwise it can be implemented in phases for validation, example Two-Phase simplex method.  ANALYSIS A model can analyse the data but it cannot be better than the information that goes into it. It means data can be interpreted but cannot be generated.  MODELS ARE FOR THE DECISION MAKERS OR models are to aid the decision maker but not to replace them. The decision is to be taken by the management e.g. In LPP X1 = 0 X2 = 9 X1 = 6 or X2 = 3 Say, in the above multiple optimal solution is provided by LPP giving same total profits. It is for the management to decide whether to discontinue the product X1 or continue to produce X1 because the total profits are the profits are the same.

 A MODEL SHOULD NEVER BE TAKE TOO LITERALLY It means it does not provide unique answer. In sensitivity analyses, or under simulation, we can find still better results.  FLEXIBLE MODEL A model should be flexible enough to incorporate changes. It should give range where one solution is valid as in case of sensitivity analysis  SEEK COOPERATION FROM OR EXPERTS As we know the tested results of the model are implemented. It is to be done by OR expert results.  USE OF COMPUTERS Use of computers is made where ever possible in case of implementation of models. OR techniques are usually complex and only computers can solve them. Hence, steps should be clearly stated to unable the OR researcher to develop computer software for future implementation of the techniques.

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