Almond's analysis is known as structural functionalismi The yard-stick with which political systems are measured consists of the functions which are performed by the political system and the units which are being compared are the various structures which compose individual political systems. Once the functions of a political system are defined operationally and the structures categorised with precision, it will become, Almond asserts, possible to writei an equation of each political system which will show how much of each function is fulfilled by a particular structure. This Almond describes as the probabilistic theory of the polity'