On the Timing and Efficiency of Creative Destruction

This paper analyzes the timing, pace and efficiency of the on- going job reallocation that results from product and process innovation. There are strong reasons why an efficient economy ought to concentrate both job creation and destruction during cyclical downturns, when the opportunity cost of reallocation is lowest. Malfunctioning labor markets can disrupt this synchronized pattern and decouple creation and destruction. Moreover, irrespective of whether workers are too strong or too weak, labor market inefficiencies generally lead to technological 'sclerosis,' characterized by excessively slow renovation. Government incentives to production may alleviate high unemployment in this economy, but at the cost of exacerbating sclerosis. Creation incentives, on the contrary, increase the pace of reallocation. We show how an optimal combination of both types of policies can restore economic efficiency.

Speculative Growth

We propose a framework for understanding recurrent historical episodes of vigorous economic expansion accompanied by extreme asset valuations, as exhibited by Japan in the 1980's and the U.S. in the 1990's. We interpret this phenomenon as a high-valuation equilibrium with a low effective cost of capital based on optimism about the future availability of funds for investment. The key to the sustainability of such equilibrium is feedback from increased growth to an increase in the supply of funding. We show that such feedback arises naturally when the expansion is concentrated in a new economy' sector and when it is supported by sustained financial surpluses-both of which would constitute an integral part, as cause and consequence, of a speculative growth' equilibrium. The high-valuation equilibrium we analyze may take the form of a stock market bubble. In contrast to classic bubbles on non-productive assets, the bubbles in our model encourage real investments, boost long run savings, and may appear in dynamically efficient economies.

Creative Destruction and Development: Institutions, Crises, and Restructuring

There is increasing empirical evidence that creative destruction, driven by experimentation and the adoption of new products and processes when investment is sunk, is a core mechanism of development. Obstacles to this process are likely to be obstacles to the progress in standards of living. Generically, underdeveloped and politicized institutions are a major impediment to a well-functioning creative destruction process, and result in sluggish creation, technological sclerosis,' and spurious reallocation. Those ills reflect the macroeconomic consequences of contracting failures in the presence of sunk investments. Recurrent crises are another major obstacle to creative destruction. The common inference that increased liquidations during crises result in increased restructuring is unwarranted. Indications are, to the contrary, that crises freeze the restructuring process and that this is associated with the tight financial-market conditions that follow. This productivity cost of recessions adds to the traditional costs of resource under-utilization.

The Cost of Recessions Revisited: A Reverse-Liquidationist View

The observation that liquidations are concentrated in recessions has long been the subject of controversy. One view holds that liquidations are beneficial in that they result in increased restructuring. Another view holds that liquidations are privately inefficient and essentially wasteful. This paper proposes an alternative perspective. Based on a combination of theory and empirical evidence on gross job flows and on financial and labor market rents, we find that, cumulatively, recessions result in reduced restructuring, and that this is likely to be socially costly once we consider inefficiencies on both the creation and destruction margins.

A hierarchical Bayesian model for predicting ecological interactions using scaled evolutionary relationships

Identifying undocumented or potential future interactions among species is a challenge facing modern ecologists. Recent link prediction methods rely on trait data, however large species interaction databases are typically sparse and covariates are limited to only a fraction of species. On the other hand, evolutionary relationships, encoded as phylogenetic trees, can act as proxies for underlying traits and historical patterns of parasite sharing among hosts. We show that using a network-based conditional model, phylogenetic information provides strong predictive power in a recently published global database of host-parasite interactions. By scaling the phylogeny using an evolutionary model, our method allows for biological interpretation often missing from latent variable models. To further improve on the phylogeny-only model, we combine a hierarchical Bayesian latent score framework for bipartite graphs that accounts for the number of interactions per species with the host dependence informed by phylogeny. Combining the two information sources yields significant improvement in predictive accuracy over each of the submodels alone. As many interaction networks are constructed from presence-only data, we extend the model by integrating a correction mechanism for missing interactions, which proves valuable in reducing uncertainty in unobserved interactions.Comment: To appear in the Annals of Applied Statistic