The Experts below are selected from a list of 1746 Experts worldwide ranked by ideXlab platform
Chad Syverson - One of the best experts on this subject based on the ideXlab platform.
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healthcare exceptionalism productivity and allocation in the u s healthcare sector
Research Papers in Economics, 2013Co-Authors: Amitabh Chandra, Amy Finkelstein, Adam Sacarny, Chad SyversonAbstract:The conventional wisdom in health economics is that large differences in average productivity across hospitals are the result of idiosyncratic, institutional features of the healthcare sector which dull the role of market forces. Strikingly, however, we find that productivity dispersion in heart attack treatment across hospitals is, if anything, smaller than in narrowly defined manufacturing industries such as Ready-Mixed Concrete. While this fact admits multiple interpretations, we also find evidence against the conventional wisdom that the healthcare sector does not operate like an industry subject to standard market forces. In particular, we find that hospitals that are more productive at treating heart attacks have higher market shares at a point in time and are more likely to expand over time. For example, a 10 percent increase in hospital productivity today is associated with about 4 percent more patients in 5 years. Taken together, these facts suggest that the healthcare sector may have more in common with "traditional" sectors than is often assumed.
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cementing relationships vertical integration foreclosure productivity and prices
Journal of Political Economy, 2007Co-Authors: Ali Hortacsu, Chad SyversonAbstract:This paper empirically investigates the possible market power effects of vertical integration proposed in the theoretical literature on vertical foreclosure. It uses a rich data set of cement and Ready‐Mixed Concrete plants that spans several decades to perform a detailed case study. There is little evidence that foreclosure is quantitatively important in these industries. Instead, prices fall, quantities rise, and entry rates remain unchanged when markets become more integrated. These patterns are consistent, however, with an alternative efficiency‐based mechanism. Namely, higher‐productivity producers are more likely to vertically integrate and are also larger, more likely to survive, and more likely to charge lower prices. We find evidence that integrated producers’ productivity advantage is tied to improved logistics coordination afforded by large local Concrete operations. Interestingly, this benefit is not due to firms’ vertical structures per se: nonvertical firms with large local Concrete operatio...
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cementing relationships vertical integration foreclosure productivity and prices
National Bureau of Economic Research, 2007Co-Authors: Ali Hortacsu, Chad SyversonAbstract:This paper empirically investigates the possible market power effects of vertical integration proposed in the theoretical literature on vertical foreclosure. It uses a rich data set of cement and Ready-Mixed Concrete plants that spans several decades to perform a detailed case study. There is little evidence that foreclosure is quantitatively important in these industries. Instead, prices fall, quantities rise, and entry rates remain unchanged when markets become more integrated. These patterns are consistent, however, with an alternative efficiency-based mechanism. Namely, higher productivity producers are more likely to vertically integrate and are also larger, more likely to survive, and charge lower prices. We find evidence that integrated producers' productivity advantage is tied to improved logistics coordination afforded by large local Concrete operations. Interestingly, this benefit is not due to firms' vertical structures per se: non-vertical firms with large local Concrete operations have similarly high productivity levels.
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market structure and productivity a Concrete example
Journal of Political Economy, 2004Co-Authors: Chad SyversonAbstract:Many studies have documented large and persistent productivity differences across producers, even within narrowly defined industries. This paper both extends and departs from the past literature, which focused on technological explanations for these differences, by proposing that demand-side features also play a role in creating the observed productivity variation. The specific mechanism investigated here is the effect of spatial substitutability in the product market. When producers are densely clustered in a market, it is easier for consumers to switch between suppliers (making the market in a certain sense more competitive). Relatively inefficient producers find it more difficult to operate profitably as a result. Substitutability increases truncate the productivity distribution from below, resulting in higher minimum and average productivity levels as well as less productivity dispersion. The paper presents a model that makes this process explicit and empirically tests it using data from U.S. Ready-Mixed Concrete plants, taking advantage of geographic variation in substitutability created by the industry's high transport costs. The results support the model's predictions and appear robust. Markets with high demand density for Ready-Mixed Concrete and thus high Concrete plant densities have higher lower-bound and average productivity levels and exhibit less productivity dispersion among their producers.
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market structure and productivity a Concrete example
Research Papers in Economics, 2001Co-Authors: Chad SyversonAbstract:This paper shows that imperfect output substitutability explains part of the observed persistent plant-level productivity dispersion. Specifically, as substitutability in a market increases, the market’s productivity distribution exhibits falling dispersion and higher central tendency. The proposed mechanism behind this result is truncation of the distribution from below as increased substitutability shifts demand to lower-cost plants and drives inefficient plants out of business. In a case study of the Ready-Mixed Concrete industry, I examine the impact of one manifestation of this effect, driven by geographic market segmentation resulting from transport costs. A theoretical foundation is presented characterizing how differences in the density of local demand impact the number of producers and the ability of customers to choose between suppliers, and through this, the equilibrium productivity and output levels across regions. I also introduce a new method of obtaining plant-level productivity estimates that is well suited to this application and avoids potential shortfalls of commonly used procedures. I use these estimates to empirically test the presented theory, and the results support the predictions of the model. Local demand density has a significant influence on the shape of plant-level productivity distributions, and accounts for part of the observed intra-industry variation in productivity, both between and within given market areas.
Ali Hortacsu - One of the best experts on this subject based on the ideXlab platform.
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cementing relationships vertical integration foreclosure productivity and prices
Journal of Political Economy, 2007Co-Authors: Ali Hortacsu, Chad SyversonAbstract:This paper empirically investigates the possible market power effects of vertical integration proposed in the theoretical literature on vertical foreclosure. It uses a rich data set of cement and Ready‐Mixed Concrete plants that spans several decades to perform a detailed case study. There is little evidence that foreclosure is quantitatively important in these industries. Instead, prices fall, quantities rise, and entry rates remain unchanged when markets become more integrated. These patterns are consistent, however, with an alternative efficiency‐based mechanism. Namely, higher‐productivity producers are more likely to vertically integrate and are also larger, more likely to survive, and more likely to charge lower prices. We find evidence that integrated producers’ productivity advantage is tied to improved logistics coordination afforded by large local Concrete operations. Interestingly, this benefit is not due to firms’ vertical structures per se: nonvertical firms with large local Concrete operatio...
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cementing relationships vertical integration foreclosure productivity and prices
National Bureau of Economic Research, 2007Co-Authors: Ali Hortacsu, Chad SyversonAbstract:This paper empirically investigates the possible market power effects of vertical integration proposed in the theoretical literature on vertical foreclosure. It uses a rich data set of cement and Ready-Mixed Concrete plants that spans several decades to perform a detailed case study. There is little evidence that foreclosure is quantitatively important in these industries. Instead, prices fall, quantities rise, and entry rates remain unchanged when markets become more integrated. These patterns are consistent, however, with an alternative efficiency-based mechanism. Namely, higher productivity producers are more likely to vertically integrate and are also larger, more likely to survive, and charge lower prices. We find evidence that integrated producers' productivity advantage is tied to improved logistics coordination afforded by large local Concrete operations. Interestingly, this benefit is not due to firms' vertical structures per se: non-vertical firms with large local Concrete operations have similarly high productivity levels.
Pusit Lertwattanaruk - One of the best experts on this subject based on the ideXlab platform.
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use of Ready Mixed Concrete plant sludge water in Concrete containing an additive or admixture
Journal of Environmental Management, 2009Co-Authors: Burachat Chatveera, Pusit LertwattanarukAbstract:Abstract In this study, we investigated the feasibility of using sludge water from a Ready-Mixed Concrete plant as mixing water in Concrete containing either fly ash as an additive or a superplasticizer admixture based on sulfonated naphthalene-formaldehyde condensates (SNF). The chemical and physical properties of the sludge water and the dry sludge were investigated. Cement pastes were Mixed using sludge water containing various levels of total solids content (0.5, 2.5, 5, 7.5, 10, 12.5, and 15%) in order to determine the optimum content in the sludge water. Increasing the total solids content beyond 5–6% tended to reduce the compressive strength and shorten the setting time. Concrete mixes were then prepared using sludge water containing 5–6% total solids content. The Concrete samples were evaluated with regard to water required, setting time, slump, compressive strength, permeability, and resistance to acid attack. The use of sludge water in the Concrete mix tended to reduce the effect of both fly ash and superplasticizer. Sludge water with a total solids content of less than 6% is suitable for use in the production of Concrete with acceptable strength and durability.
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effect of sludge water from Ready Mixed Concrete plant on properties and durability of Concrete
Cement & Concrete Composites, 2006Co-Authors: Burachat Chatveera, Pusit LertwattanarukAbstract:Besides the increasing disposal cost, sludge water, a wastewater washout from Ready-Mixed Concrete plant, has caused environmental impact problems. This paper investigates the utilization and recycling of sludge water as mixing water for Concrete production. The basic properties of sludge water were obtained according to ASTM standards. The properties of dry sludge powder such as chemical compositions and physical properties were investigated. The properties of fresh Concrete studied were unit weight, slump, and temperature rise. The mechanical properties of Concrete, such as compressive strength and modulus of elasticity, were studied. The durability aspects, such as drying shrinkage and weight loss due to acid attack, were investigated. For parametric study, sludge water was used as a replacement of tap water varying from 0% to 100% by weight. The water-to-cement ratios were 0.5, 0.6, and 0.7, respectively. In this study the sludge water tested has a high alkalinity and the total solids content exceeding the limit of ASTM C94, contributing to the more porous and weaker matrix. As a result, when increasing the percentage of sludge water in mixing water, the drying shrinkage and weight loss due to acid attacks increased, and the slump and strength decreased. However, the unit weight and temperature of fresh Concrete were not affected by the use of sludge water.
Burachat Chatveera - One of the best experts on this subject based on the ideXlab platform.
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use of Ready Mixed Concrete plant sludge water in Concrete containing an additive or admixture
Journal of Environmental Management, 2009Co-Authors: Burachat Chatveera, Pusit LertwattanarukAbstract:Abstract In this study, we investigated the feasibility of using sludge water from a Ready-Mixed Concrete plant as mixing water in Concrete containing either fly ash as an additive or a superplasticizer admixture based on sulfonated naphthalene-formaldehyde condensates (SNF). The chemical and physical properties of the sludge water and the dry sludge were investigated. Cement pastes were Mixed using sludge water containing various levels of total solids content (0.5, 2.5, 5, 7.5, 10, 12.5, and 15%) in order to determine the optimum content in the sludge water. Increasing the total solids content beyond 5–6% tended to reduce the compressive strength and shorten the setting time. Concrete mixes were then prepared using sludge water containing 5–6% total solids content. The Concrete samples were evaluated with regard to water required, setting time, slump, compressive strength, permeability, and resistance to acid attack. The use of sludge water in the Concrete mix tended to reduce the effect of both fly ash and superplasticizer. Sludge water with a total solids content of less than 6% is suitable for use in the production of Concrete with acceptable strength and durability.
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effect of sludge water from Ready Mixed Concrete plant on properties and durability of Concrete
Cement & Concrete Composites, 2006Co-Authors: Burachat Chatveera, Pusit LertwattanarukAbstract:Besides the increasing disposal cost, sludge water, a wastewater washout from Ready-Mixed Concrete plant, has caused environmental impact problems. This paper investigates the utilization and recycling of sludge water as mixing water for Concrete production. The basic properties of sludge water were obtained according to ASTM standards. The properties of dry sludge powder such as chemical compositions and physical properties were investigated. The properties of fresh Concrete studied were unit weight, slump, and temperature rise. The mechanical properties of Concrete, such as compressive strength and modulus of elasticity, were studied. The durability aspects, such as drying shrinkage and weight loss due to acid attack, were investigated. For parametric study, sludge water was used as a replacement of tap water varying from 0% to 100% by weight. The water-to-cement ratios were 0.5, 0.6, and 0.7, respectively. In this study the sludge water tested has a high alkalinity and the total solids content exceeding the limit of ASTM C94, contributing to the more porous and weaker matrix. As a result, when increasing the percentage of sludge water in mixing water, the drying shrinkage and weight loss due to acid attacks increased, and the slump and strength decreased. However, the unit weight and temperature of fresh Concrete were not affected by the use of sludge water.
Byongjeong Choi - One of the best experts on this subject based on the ideXlab platform.
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direct tensile strength of lightweight Concrete with different specimen depths and aggregate sizes
Construction and Building Materials, 2014Co-Authors: Sejin Choi, Keunhyeok Yang, Jaeil Sim, Byongjeong ChoiAbstract:Abstract To examine the size effect in direct tension, 8 Ready-Mixed Concrete batches classified into all-lightweight Concrete (ALWC) and sand-lightweight Concrete (SLWC) groups were prepared. In each group, the maximum aggregate size varied between 4 mm and 19 mm, and then the lateral depth of specimen with rectangular section ranged from 100 mm to 500 mm in each Concrete batch. The size effect curves based on the basic formulas proposed by Bažant (1984) [1], Kim and Eo (1990) [2], and Yang and Sim (2011) [3] were also determined using a total of 28 lightweight Concrete (LWC) data of current tests and 114 normal-weight Concrete (NWC) data compiled from the available literature (Carpinteri and Ferro, 1994; Hu, 2011) [4,5], though specimens with lateral depth beside 100 mm is very insufficient even in NWC. The present experimental observations and verifications by prediction models clearly showed that the size effect is more notable with the decrease of the unit weight of Concrete and it is stronger in direct tension than in compression. The validity of Bažant’s model (Bažant, 1984) [1] is significantly dependent on the maximum aggregate size, while the models proposed by Kim and Eo (1990) [2] and Yang and Sim (2011) [3] closely predict the size effect trend observed from test data, confirming that the influence of the maximum aggregate size on the Concrete tensile strength and the size effect is negligible, especially for LWC.
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size and shape effects on compressive strength of lightweight Concrete
Construction and Building Materials, 2013Co-Authors: Keunhyeok Yang, Byongjeong ChoiAbstract:Abstract In this study, the size and aspect ratio effects on the compressive strength of lightweight Concrete were examined using nine laboratorial Concrete mixes and three Ready-Mixed Concrete batches. At each Concrete mix, the aspect ratios of specimens with circular or square sections were 1.0 and 2.0. The lateral dimension of specimens ranged between 50 and 150 mm at each laboratorial Concrete mix, while it varied from 50 to 400 mm at each Ready-Mixed Concrete batch. The present study also proposed generalized prediction models for the size effect based on the crack band theory of fracture mechanics, which can cover important influencing parameters such as the aspect ratio and lateral depth of the specimen and the unit weight of Concrete. Test results showed that the crack band zone in lightweight Concrete specimens was more localized with poor crack distribution than in normal-weight Concrete specimens, regardless of the geometrical dimensions of the specimens. As a result, the size effect was stronger with the decrease of the Concrete unit weight, and this trend was more notable in specimens with an aspect ratio of 2.0 than in those with an aspect ratio of 1.0. The compressive strength predictions of Concrete obtained from the present models are in good agreement with the test results including a total of 1661 data. The trend of the size effect against different parameters as predicted by the present models has a consistent agreement with that observed from experimental results.
