Is lumpy investment relevant for the business cycle?

Previous research has suggested that discrete and occasional plant-level capital adjustments have significant aggregate implications. In particular, it has been argued that changes in plants? willingness to invest in response to aggregate shocks can at times generate large movements in total investment demand. In this study, I re-assess these predictions in a general equilibrium environment. Specifically, assuming nonconvex costs of capital adjustment, I derive generalized (S,s) adjustment rules yielding lumpy plant-level investment within an otherwise standard equilibrium business cycle model. In contrast to previous partial equilibrium analyses, model results reveal that the aggregate effects of lumpy investment are negligible. In general equilibrium, households? preference for relatively smooth consumption profiles offsets changes in aggregate investment demand implied by the introduction of lumpy plant-level investment. As a result, adjustments in wages and interest rates yield quantity dynamics that are virtually indistinguishable from the standard model.Business cycles ; Investments

Inventories and the business cycle: an equilibrium analysis of (S,s) policies.

The authors develop an equilibrium business cycle model in which final goods producers pursue generalized (S,s) inventory policies with respect to intermediate goods, a consequence of nonconvex factor adjustment costs. Calibrating their model to reproduce the average inventory-to-sales ratio in postwar U.S. data, the authors find that it explains half of the cyclical variability of inventory investment. Moreover, inventory accumulation is strongly procyclical, and production is more volatile than sales, as in the data. The comovement between inventory investment and final sales is often interpreted as evidence that inventories amplify aggregate fluctuations. However, the authors' model economy exhibits a business cycle similar to that of a comparable benchmark without inventories.Inventories ; Business cycles

Nonconvex factor adjustments in equilibrium business cycle models: do nonlinearities matter?

Using an equilibrium business cycle model, the authors search for aggregate nonlinearities arising from the introduction of nonconvex capital adjustment costs. The authors find that while such adjustment costs lead to nontrivial nonlinearities in aggregate investment demand, equilibrium investment is effectively unchanged. This finding, based on a model in which aggregate fluctuations arise through exogenous changes in total factor productivity, is robust to the introduction of shocks to the relative price of investment goods.Business cycles

Modeling Inventories Over the Business Cycle

We search for useful models of aggregate fluctuations with inventories. We focus exclusively on dynamic stochastic general equilibrium models that endogenously give rise to inventory investment and evaluate two leading candidates: the (S,s) model and the stockout avoidance model. Each model is examined under both technology shocks and preference shocks, and its performance gauged by its ability to explain the observed magnitude of inventories in the U.S. economy, alongside other empirical regularities such as the procyclicality of inventory investment and its positive correlation with sales. We find that the (S,s) model is far more consistent with the behavior of aggregate inventories in the postwar U.S. when aggregate fluctuations arise from technology, rather than preference, shocks. The converse is true for the stockout avoidance model. Overall, while the (S,s) model performs well with respect to the inventory facts and other business cycle regularities, the stockout avoidance model does not. There, the essential motive for stocks is insufficient to generate inventory holdings near the data without destroying the model's performance along other important margins. Finally, the stockout avoidance model appears incapable of sustaining inventories alongside capital. This suggests a fundamental problem in using reduced-form inventory models with stocks rationalized by this motive.

Idiosyncratic shocks and the role of nonconvexities in plant and aggregate investment dynamics.

We solve equilibrium models of lumpy investment wherein establishments face persistent shocks to common and plant-specific productivity. Nonconvex adjustment costs lead plants to pursue generalized (S,s) decision rules with respect to capital; as a result, their individual investments are lumpy. In partial equilibrium, this yields substantial skewness and kurtosis in aggregate investment, though with differences in plant-level productivity, these nonlinearities are far less pronounced. Moreover, nonconvex costs, like quadratic adjustment costs, greatly increase the persistence of aggregate investment rates, yielding a better match with the data. ; In general equilibrium, aggregate nonlinearities disappear, and investment rates are very persistent, regardless of capital adjustment costs. While the aggregate implications of lumpy investment change substantially in equilibrium, the inclusion of fixed costs or idiosyncratic shocks yields an average distribution of plant investment rates that, in contrast, is largely unaffected by market-clearing movements in real wages and interest rates. Nonetheless, we find that to understand the dynamics of plant-level investment requires general equilibrium analysis.Investments ; Productivity

Modeling inventories over the business cycle.

We search for useful models of aggregate fluctuations with inventories. We focus exclusively on dynamic stochastic general equilibrium models that endogenously give rise to inventory investment and evaluate two leading candidates: the (S,s) model and the stockout avoidance model. Each model is examined under both technology shocks and preference shocks, and its performance gauged by its ability to explain the observed magnitude of inventories in the U.S. economy, alongside other empirical regularities, such as the procyclicality of inventory investment and its positive correlation with sales. We find that the (S,s) model is far more consistent with the behavior of aggregate inventories in the postwar U.S. when aggregate fluctuations arise from technology, rather than preference, shocks. The converse is true for the stockout avoidance model. Overall, while the (S,s) model performs well with respect to the inventory facts and other business cycle regularities, the stockout avoidance model does not. There, the essential motive for stocks is insufficient to generate inventory holdings near the data without destroying the model’s performance along other important margins. Finally, the stockout avoidance model appears incapable of sustaining inventories alongside capital. This suggests a fundamental problem in using reduced-form inventory models with stocks rationalized by this motiveInventories ; Business cycles

Idiosyncratic Shocks and the Role of Nonconvexities in Plant and Aggregate Investment Dynamics

We examine a model of lumpy investment wherein establishments face persistent shocks to common and plant-specific productivity, and nonconvex adjustment costs lead them to pursue generalized (S,s) investment rules. We allow persistent heterogeneity in both capital and total factor productivity alongside low-level investments exempt from adjustment costs to develop the first model consistent with available evidence on establishment-level investment rates. Reassessing the implications of lumpy investment for aggregate dynamics in this setting, we find that they remain substantial when factor supply considerations are ignored, but are quantitatively irrelevant in general equilibrium. The substantial implications of general equilibrium extend beyond the dynamics of aggregate series. While the presence of idiosyncratic shocks makes the time-averaged distribution of plant-level investment rates largely invariant to market-clearing movements in real wages and interest rates, we show that the dynamics of plants' investments differ sharply in their presence. Thus, model-based estimations of capital adjustment costs involving panel data may be quite sensitive to the assumption about equilibrium. Our analysis also offers new insights about how nonconvex adjustment costs influence investment at the plant. When establishments face large and weakly persistent idiosyncratic productivity shocks consistent with existing estimates, we find that nonconvex costs do not cause lumpy investments, but act to eliminate them(S,s) policies, lumpy investment, quantitative general equilibrium

Idiosyncratic shocks and the role of nonconvexities in plant and aggregate investment dynamics

The authors study a model of lumpy investment wherein establishments face persistent shocks to common and plant-specific productivity, and nonconvex adjustment costs lead them to pursue generalized (S,s) investment rules. They allow persistent heterogeneity in both capital and total factor productivity alongside low-level investments exempt from adjustment costs to develop the first model consistent with the cross-sectional distribution of establishment investment rates. Examining the implications of lumpy investment for aggregate dynamics in this setting, the authors find that they remain substantial when factor supply considerations are ignored, but are quantitatively irrelevant in general equilibrium. ; The substantial implications of general equilibrium extend beyond the dynamics of aggregate series. While the presence of idiosyncratic shocks makes the time-averaged distribution of plant-level investment rates largely invariant to market-clearing movements in real wages and interest rates, the authors show that the dynamics of plants' investments differ sharply in their presence. Thus, model-based estimations of capital adjustment costs involving panel data may be quite sensitive to the assumption about equilibrium. Their analysis also offers new insights about how nonconvex adjustment costs influence investment at the plant. When establishments face idiosyncratic productivity shocks consistent with existing estimates, they find that nonconvex costs do not cause lumpy investments, but act to eliminate them.Investments

The Magnetic Field in the Solar Atmosphere

This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quiet Sun and coronal holes.Comment: 109 pages, 30 Figures, to be published in A&AR

Modeling inventories over the business cycle

We evaluate two leading models of aggregate fluctuations with inventories in general equilibrium: the (S,s) model and the stockout avoidance model. Each is judged by its ability to explain the observed magnitude of inventories in the U.S. economy, alongside other empirical regularities such as the procyclicality of inventory investment and its positive correlation with sales. We find that the (S,s) model is far more consistent with the behavior of aggregate inventories in the postwar U.S. when aggregate fluctuations arise from technology, rather than preference, shocks. The converse holds for the stockout avoidance model. The (S,s) model performs well with respect to the inventory facts and other business cycle regularities. By contrast, the essential risk motive in the stockout avoidance model is insufficient to generate inventory holdings near the data without destroying the model's performance elsewhere, suggesting a fundamental problem in using reduced-form inventory models with stocks rationalized by this motive.Inventories ; Business cycles