Before proposing complex theories to explain sociological phenomena (e.g., World Systems Theory), especially at the macro and/or societal levels, sociologists should first turn to demographic indicators for possible explanations. Demographic analysis is a powerful tool that can explain a number of sociological phenomena.
For instance, in examining the elements that led to the first World War, most people turn to political and diplomatic conflicts but fail to consider the implications of expanding populations in the European countries involved. Expanding populations will result in increased competition for resources (i.e., food, land, access to trade routes and ports, etc.). Expanding populations may not be the primary cause of World War I, but it may have played a role in the increased hostilities leading up to the war. In this fashion, demographic indicators are often informative in explaining world events and should be turned to first as explanations.