Urban sociology even has a subset termed neighbourhood sociology which supports the study of local communities [17] and the diversity of urban neighbourhoods.[18] Neighbourhoods are also used in research studies from postal codes and health disparities, to correlations with school drop out rates or use of drugs.[19] Central yet today are "community values" which have changed dramatically in larger cities, and sometimes not as much in rural regions of the USA; these values are reflected and shaped in part by the media bridging the gap between citizens and government.[20]