Observation of the behaviour, attitudes and opinions, among other things, of a population can be done to achieve many objectives. Much of such studies belong to the field of market research, and much to social research. Opinion polling is included in the social research field, but is distinguished as a sub-category by its direct relevance to a national or other political process. The distinction is not always clear; for instance a survey on attitudes to abortion need or need not fall into the opinion polling category according to whether or not abortion is currently a matter of political debate. But it can also be said that like genius, or sex appeal, an opinion poll is difficult to define but easy to recognise when you see it. Typically, opinion polls relate to possible voting behaviour, attitudes to political personalities and issues. As such their existence round the world, so say nothing of what they do, reveals interesting patterns.