Macroeconomic theories take polar views on the importance of choice versus chance. At the micro level, it seems realistic to assume that both dimensions play a role for individual employment outcomes, although it might be difficult to separate these two effects. Nevertheless the choice and...

Parametric aggregation of heterogeneous micro production technologies is discussed. A four-factor Cobb-Douglas function with normally distributed firm specific coefficients and with log-normal inputs (which agrees well with the available data) is speciffied. Since, if the number of micro units...

How do firms differ, and why do they di.er even within narrowly defined industries? Using evidence from six high-tech, manufacturing industries covering a 24-year period, we show that di.erences in sales, materials, labor costs and capital across firms can largely be summarized by a single,...