Measuring middle-class decline in one and many attributes

A new multivariate approach is introduced to identify the middle class of a society and to measure its possible decline. The middle class is a properly defined central region in attribute space that contains a fixed portion of the population. The decline of the middle class is measured by comparing the dispersion of the middle class. The use of minimum volume ellipsoids and different notions of central regions is discussed in one and several dimensions. An empirical illustration is given using German data on income and wealth.