ABSTRACT
The essence of the experiment is that the researcher aims to control all the relevant variables in the research environment. The experimental approach is closely associated with the positivist paradigm and is consistent with the classic scientific model of testing hypotheses and seeking to establish cause and effect relationships. In a natural science experiment, the subjects will be identical specimens or samples of organic or inorganic matter, or laboratory animals that are as nearly as possible identical, and are treated identically except for the experimental treatment. Imagine a medical scientist searching for a drug to treat a virus: a number of possibilities may be explored before a successful treatment is discovered. The researchers found a positive relationship between engagement in physical activity and mood level, with the greatest effect being when people started the activity in a depressed mood. In this quasi-experimental method the selection of the 'treatment' and the pre-test observations are under the control of the subjects.
