We introduce a two-dimensional measure for the heterogeneity of performance within groups. It leads to a much more differentiated description of heterogeneity than alternative measures and it is relatively robust with regard to extreme values of small units ('outliers').

The impact of new business formation on regional employment has been investigated. The main effects occur after a considerable time lag. Obviously, a large part of the effect is not due to job creation by the newcomers but rather is of indirect nature. This implies that a large part of the...