Experimental techniques in engineering are generally used in the following contexts.

1. To explore system performance under a variety of input conditions. (This is also called process identification )

2. To generate calibration data for parameter estimation.

3. To test hypothesis which go into building a mathematical model.

Irrespective of the final goal, experiments have to be carried out on a definite piece of hardware with all the accompanying instruments and measurement systems. For systems that are massive in size, a scaling down may be required; for those which are miniature systems a scaling up operation is required. Accordingly, the measured data will have to be scaled before being applied to the real systems. Scaling principles are often referred as similitude. Scaling principles can be developed in many applications by performing a dimensional analysis of the input (controlled) and output (uncontrolled) variables.