A Theoretical Foundation for Understanding Firm Size Distributions and Gibrat's Law

This paper presents a dynamic model of the firm size distribution. Empirical studies of the firm size distribution often compare the moments to a log-normal distribution as implied by Gibrat's Law and note important deviations. Thus, the first, and basic questions we ask are how well does the dynamic industry model reproduce Gibrat's Law and how well does it match the deviations uncovered in the literature. We show that the model reproduces these results when testing the simulated output using the techniques of the empirical literature. We then use the model to study how structural parameters affect the firm size distribution. We find that, among other things, fixed and sunk costs increase both the mean and variance of the firm size distribution while generally decreasing the skewness and kurtosis. The rate of growth in an industry also raises the mean and variance, but has non-monotonic effects on the higher moments.Firm size distribution; Gibrat's Law; R&D.

Investigation of the Flow and Fate of Nitrate in Epikarst at the Savoy Experimental Watershed, Northwest Arkansas

Many karst aquifers are at high risk of nitrate contamination due to a combination of vulnerable geology characterized by thin soils and conduit flow, and excess inputs of nutrients from animal feeding operations. One zone that is present in many karst regions and could play an important role in nitrate attenuation due to properties such as increased residence time and matrix-water contact is the upper, weathered portion of karst, the epikarst. However, the understanding of this role is lacking, and the objective of this dissertation was to elucidate it. The fate of nitrate in the epikarst was traced along a hydrologic gradient using a multi-faceted geochemical approach based primarily on concentration and stable isotope composition of the reactants and products of denitrification. In addition, dye-tracing tests were conducted to assess the flow, solute transport and aquifer characteristics of the epikarst system. The study found multiple lines of evidence for denitrification which is spatially and temporally highly variable and can remove up to 33% of nitrate along the studied flowpaths. Dissolved organic carbon and dissolved oxygen appear to control denitrification levels, and both in turn appear to be controlled by hydrologic conditions (saturation). However, the most significant agent of nitrate attenuation is dilution, decreasing nitrate concentration by upwards of 50%. Transport of water and solutes in the epikarst can be relatively fast (up to 2.2 m/h) and involves preferential flowpaths. However, transport of a point-source solute located in the upper epikarst depends on saturation, and the transported mass is likely to be negligible in the short term (weeks-months) under the normal weather pattern. Overall, the results indicate that the epikarst can be an important buffer against potential groundwater contaminants

Understanding the Variations in Gibrat's Law with a Markov-Perfect Dynamic Industry Model

Gibrat's Law of proportionate effect, as applied to firms, states that the growth rate of a firm is independent of its size. Empirical work on firm dynamics finds crucial deviations from Gibrat's Law such as smaller firms growing faster than larger firms (Evans, 1987, and Hall, 1987), a negative relationship between the variance of growth rates and size (Dunne and Hughes, 1994), and first-order positive autocorrelation in the growth rates (Kumar, 1995). Moreover, the degree of deviation from Gibrat's Law varies across industries. This paper contributes to our understanding of the forces that make Gibrat's Law a close, but imperfect approximation of firm size distributions and seeks to determine potential sources of cross-industry variation. Here, we employ an extension of the Ericson-Pakes (1995) theoretical framework that allows for firm growth developed by Laincz (2004a). By varying key parameters, the simulations demonstrate potential sources for the various, and sometimes conflicting, results on Gibrat's Law uncovered in the empirical literatureGibrat's Law, Firm Size Distribution, Entry, Exit

Scale Effects, An Error of Aggregation Not Specification: Empirical Evidence

In a set of influential papers, Charles Jones (1995a, 1995b, 1999) argued that R&D based endogenous growth models are inconsistent with the data. He showed, in a very striking manner, that the scale effects prediction of early endogenous growth models (e.g. Romer, 1986 and 1990, Grossman and Helpman, 1991, and Aghion and Howitt, 1992) is not borne out in the data. Standard endogenous growth models attribute constant or increasing returns in the stock of knowledge or technology to the aggregate level of resources. This assumption leads to the counterfactual prediction that the rate of productivity growth should be increasing in the aggregate amount of resources devoted to accumulating knowledge. This paper presents empirical evidence in support of R&D based endogenous growth models without scale effects (e.g. Young, 1998, Howitt, 1999, Thompson, 2001, and Peretto and Smulders, 2002). In these models the average level of workers or R&D workers per firm drives growth as opposed to the aggregate level and do not share the scale effects property in the limit. Using data for the US covering 1964-2001, we show that when the number of employees or scientists/engineers are scaled down on a per establishment basis, the empirics support the latter version of endogenous growth models. Specifically, the long-run size of establishments is stable, neither declining or growing in the long-run, where size is measured in two ways: by workers per establishment and R&D workers per establishment. Second, we demonstrate a positive effect running from average establishment size to productivity growth as predicted by the theories.

Science and Technology Undergraduate Students\u27 Use of the Internet, Cell Phones and Social Networking Sites to Access Library Information

Many academic libraries and publishers have developed mobile-optimized versions of their web sites and catalogs. Almost all database vendors and major journal publishers have provided a way to connect to their resources via the Internet and the mobile web. In light of this pervasive use of the Internet, mobile devices and social networking, this study examines the habits of 290 science and technology students (with majors in biology (51%), chemical engineering (15%), biological engineering (9%), kinesiology (5%), and animal science (4%)), to identify whether they use this technology for library-related activities. The primary objective of this study was to identify whether the students use the Internet, their cell phones, and/or social networking sites to access scholarly information available through the library. Specifically, we were interested in finding out: (1) how often students use the Internet and for what purposes; (2) what devices they use to access library information remotely; (3) for what purposes student use their cell-phones and whether they use them to access library resources, including our social networking sites; and (4) which social networking sites students use and for what purposes. Even though there are widespread uses of the Internet, cell phones, and social networking, this study found that the majority of the students surveyed do not readily identify them as a means to access library-provided databases, the library catalog or to retrieve full-text journal articles on demand or on the go

Science and Technology Undergraduate Students\u27 Use of the Internet, Cell Phones and Social Networking Sites to Access Library Information

Many academic libraries and publishers have developed mobile-optimized versions of their web sites and catalogs. Almost all database vendors and major journal publishers have provided a way to connect to their resources via the Internet and the mobile web. In light of this pervasive use of the Internet, mobile devices and social networking, this study examines the habits of 290 science and technology students (with majors in biology (51%), chemical engineering (15%), biological engineering (9%), kinesiology (5%), and animal science (4%)), to identify whether they use this technology for library-related activities. The primary objective of this study was to identify whether the students use the Internet, their cell phones, and/or social networking sites to access scholarly information available through the library. Specifically, we were interested in finding out: (1) how often students use the Internet and for what purposes; (2) what devices they use to access library information remotely; (3) for what purposes student use their cell-phones and whether they use them to access library resources, including our social networking sites; and (4) which social networking sites students use and for what purposes. Even though there are widespread uses of the Internet, cell phones, and social networking, this study found that the majority of the students surveyed do not readily identify them as a means to access library-provided databases, the library catalog or to retrieve full-text journal articles on demand or on the go

Endogenous growth and property rights over renewable resources

We study how different regimes of access rights to renewable natural resources - namely, open access versus full property rights – affect sustainability, growth and welfare in the context of modern endogenous growth theory. Resource exhaustion may occur under both regimes but is more likely to arise under open access. Moreover, under full property rights, positive resource rents increase expenditures on manufacturing goods and temporarily accelerate productivity growth, but also yield a higher resource price at least in the short-to-medium run. We characterize analytically and quantitatively the model’s dynamics to assess the welfare implications of differences in property rights enforcement