Concept
Though the American middle class does not have a definitive definition, contemporary social scientists have put forward several ostensibly congruent theories on it. Depending on the class model used, the middle class constitutes anywhere from 25% to 75% of households. One of the first major studies of the middle class in America was White Collar: The American Middle Classes, published in 1951 by sociologist C. Wright Mills. Later sociologists such as Dennis Gilbert of Hamilton College commonly divide the middle class into two sub-groups. Constituting roughly 15% to 20% of households is the upper or professional middle class consisting of highly educated, salaried professionals and managers. Constituting roughly one third of households is the lower middle class consisting mostly of semi-professionals, skilled craftsmen and lower-level management. Middle-class persons commonly have a comfortable standard of living, significant economic security, considerable work autonomy and rely on their expertise to sustain themselves. Members of the middle class belong to diverse groups which overlap with each other. Overall, middle-class persons, especially upper-middle-class individuals, are characterized by conceptualizing, creating and consulting. Thus, college education is one of the main indicators of middle-class status. Largely attributed to the nature of middle-class occupations, middle class values tend to emphasize independence, adherence to intrinsic standards, valuing innovation and respecting non-conformity. The middle class is more politically active than other demographics. Income varies considerably, from near the national median to well in excess of US$100,000. However, household income figures do not always reflect class status and standard of living as they are largely influenced by the number of income earners and fail to recognize household size. It is therefore possible for a large, dual-earner, lower middle class household to out-earn a small, one-earner, upper middle class household.