We consider a version of the Solow growth model where technological progress can be investment specific or investment neutral. The labour market is subject to search frictions, and the existing productive units may fail to adopt the most recent technological advances. Technological progress can lead to the destruction of technologically obsolete jobs and cause unemployment. We calibrate the model to replicate the high persistence that characterizes the dynamics of firms' neutral technology and the frequency of firms' capital adjustment. We find that neutral technological advances increase job destruction and job reallocation and reduce aggregate employment. Investment-specific technological advances reduce job destruction, have mild effects on job creation, and are expansionary. Hence, neutral technological progress prompts Schumpeterian creative destruction, while investment-specific technological progress operates essentially as in the standard neoclassical growth model. Using structural VAR models, we provide support to the key dynamic implications of the model.

In this paper we present a simple, theory-based measure of the variations in aggregate economic efficiency associated with business fluctuations. We decompose this indicator, which we refer to as "the gap", into two constituent parts: a price markup and a wage markup, and show that the latter accounts for the bulk of the fluctuations in our gap measure. Finally, we derive a measure of the welfare costs of business cycles that is directly related to our gap variable, and which takes into account explicitly the existence of a varying aggregate inefficiency. When applied to postwar U.S. data, for plausible parametrizations, our measure suggests welfare losses of fluctuations that are of a higher order of magnitude than those derived by It also suggests that the major postwar recessions involved substantial efficiency costs.