Laboratory experimentation in psychology
In the simplest model, two 'treatments' (independent variables) are compared: for example, subjects are exposed to two different sound stimuli such as tones of different frequencies, to compare the effects on heart rate (dependent variable). The heart rates observed are then analysed using inferential statistics such as the 't-test' which can evaluate whether the differences are due to chance or to the two treatments.
Psychologists have explored many aspects of human and animal behaviour using this kind of approach. Advantages are that the effects of confounding variables are controlled, including the influence of observation on behaviour; disadvantages are associated with the lack of relationship to the 'real world'.