chapter  5
Design experiments: Description and outcome
Pages 24

The term ‘experiment’ usually implies a controlled experiment, but sometimes controlled experiments are prohibitively difficult or impossible, such as in the real engineering design process. In this case researchers resort to quasi-experiments, which implies that these are uncontrolled experiments (Sekaran, 2003; Robson, 2002). Quasi-experiments rely mainly on observation of the parameters of the system under study, rather than on manipulation of a few variables as occurs in controlled experiments. To the degree possible, they attempt to collect data for the system in such a way that contribution from all variables can be determined, and where the effects of variation in certain variables remain approximately constant so that the effects of other variables can be discerned.