The upper middle class is a sociological concept referring to the social group constituted by higher-status members of the middle class. This is in contrast to the term "lower middle class", which is used for the group at the opposite end of the middle class stratum, and to the broader term "middle class". There is considerable debate as to how the upper middle class might be defined. According to sociologist Max Weber the upper middle class consists of well-educated professionals with graduate degrees and comfortable incomes.