Advertising and the evolution of market structure in the US car industry

This paper focuses on a single simple stylized fact which stands out from the post-war history of the US car industry, namely that industry concentration fell just at the same time as industry advertising expenditures rose sharply. Since both events were almost certainly caused by the entry and market penetration of (largely) foreign owned car producers, this stylized fact raises interesting questions about whether – and if so, how – advertising affects entry. We use a model of consumer switching behaviour to help interpret the facts. The model predicts a simple linear association between market and advertising shares (which we observe fairly clearly at two different levels of aggregation in the data), and provides the basis for arguing that advertising can facilitate entry, but only for finite periods of time

Founding Conditions and the Survival of New Firms

We analyze the effects of founding conditions on the survival of new firms. We allow the effects of founding conditions to be transitory and estimate how long such effects last. Our findings indicate that founding effects are important determinants of exit rates. Moreover, in most cases, their effect on survival seems to persist without much of an attenuation for several years after the founding of the firm.Survival of firms; founding effects

Persistent Population Biases in Branching Random Walk Algorithms

We explore the existence of a residual population bias in Diffusion Monte Carlo algorithms. We develop a model problem, which mimics the single-particle, one dimensional simple harmonic oscillator of unitary ground state energy, to study these biases. We then apply an importance sampling algorithms with a population of a single random walker to calculate the ground state energy and wavefunction of our modeled system in cases of both perfect and imperfect importance sampling. In the former case, we perfectly calculate both the ground state energy and corresponding wavefunction of our system, thus validating our calculations and assumed answer. In the latter case, we show the existence of a residual population bias for populations of small numbers of random walkers. We demonstrate the convergence of our small population calculations and show that we cannot remove this bias through a number of single walker methods. Finally, we demonstrate the overall decay of this residual population bias as the population of random walkers expands, allowing our calculations to converge to the true answer. Key Words: Diffusion Monte Carlo, Population Dynamics, Random Wal

On the international diversification of production

This thesis is concerned with rigorously formalizing and testing a particular model of foreign investment, the so-called 'portfolio model'. As such, it is an exercise in positive economics - rigorous model specification coupled with direct empirical testing. The exercise can be conceptually separated into four stages. In the first place, consideration must be given to the reasons for using the model and the limitation on its applicability. This is the principal subject matter of the first chapter. Having cleared this ground, the model must be formulated and tested. It is here that previous attempts to test the model have been most disappointing. In Chapter II, we shall set out the model rigorously and generate an estimating technique to deal with the simultaneous equations system the model generates. The third step in our examination of the portfolio model is the assessment of the results and this merges with the final step of taking these results and using them for further explorations on multinational firms. As it turns out, the model does not command support from the data and the process of assessing the reasons for failure involve the last three chapters. However, an alternative model emerges directly from examination of the portfolio model and some attention is paid to this evolution and the close links between the models. Thus, in a sense, the thesis results are a purely negative affair - i.e. after a reasonably close examination, the portfolio model is put on one side. The reasons for failure and the beginnings of an alternative model are the positive results which emerge but, in the end, we are not left with a full blown rigorous model which we can put some confidence in. While not glorious and exhilarating, it is still progress

Abandoning Colorblind Practice in School Counseling.

Drawing from three case vignettes and the extant literature, the authors seek to identify, problematize, and expand the discussion on colorblind approaches to diversity within the practice of school counseling. The authors discuss how such an approach to working with students from traditionally under-represented groups subtly blames the victim, limits the development of equity by positioning critical dialogues as counter-productive, and inhibits the understanding of within-group differences. The article concludes with suggestions for how school counselors can enhance the services they provide to students of various social locations by abandoning colorblind practices and choosing to remove their difference blindfolds

Wave Propagation and Source Localization in Random and Refracting Media

This thesis focuses on understanding the way that acoustic and electromagnetic waves propagate through an inhomogeneous or turbulent environment, and analyzes the effect that this uncertainty has on signal processing algorithms. These methods are applied to determining the effectiveness of matched-field style source localization algorithms in uncertain ocean environments, and to analyzing the effect that random media composed of electrically large scatterers has on propagating waves. The first half of this dissertation introduces the frequency-difference autoproduct, a surrogate field quantity, and applies this quantity to passive acoustic remote sensing in waveguiding ocean environments. The frequency-difference autoproduct, a quadratic product of frequency-domain complex measured field values, is demonstrated to retain phase stability in the face of significant environmental uncertainty even when the related pressure field’s phase is as unstable as noise. This result demonstrates that a measured autoproduct (at difference frequencies less than 5 Hz) that is associated with a pressure field (measured in the hundreds of Hz) and which has propagated hundreds of kilometers in a deep ocean sound channel can be consistently cross-correlated with a calculated autoproduct. This cross-correlation is shown to give a cross-correlation coefficient that is more than 10 dB greater than the equivalent cross-correlation coefficient of the measured pressure field, demonstrating that the autoproduct is a stable alternative to the pressure field for array signal processing algorithms. The next major result demonstrates that the frequency-difference autoproduct can be used to passively localize remote unknown sound sources that broadcast sound hundreds of kilometers to a measuring device at hundreds of Hz frequencies. Because of the high frequency content of the measured pressure field, an equivalent conventional localization result is not possible using frequency-domain methods. These two primary contributions, recovery of frequency-domain phase stability and robust source localization, represent unique contributions to existing signal processing techniques. The second half of this thesis focuses on understanding electromagnetic wave propagation in a random medium composed of metallic scatterers placed within a background medium. This thesis focuses on developing new methods to compute the extinction and phase matrices, quantities related to Radiative Transfer theory, of a random medium composed of electrically large, interacting scatterers. A new method is proposed, based on using Monte Carlo simulation and full-wave computational electromagnetics methods simultaneously, to calculate the extinction coefficient and phase function of such a random medium. Another major result of this thesis demonstrates that the coherent portion of the field scattered by a configuration of the random medium is equivalent to the field scattered by a homogeneous dielectric that occupies the same volume as the configuration. This thesis also demonstrates that the incoherent portion of the field scattered by a configuration of the random medium, related to the phase function of the medium, can be calculated using buffer zone averaging. These methods are applied to model field propagation in a random medium, and propose an extension of single scattering theory that can be used to understand mean field propagation in relatively dense (tens of particles per cubic wavelength) random media composed of electrically large (up to 3 wavelengths long) conductors and incoherent field propagation in relatively dense (up to 5 particles per cubic wavelength) media composed of electrically large (up to two wavelengths) conductors. These results represent an important contribution to the field of incoherent, polarimetric remote sensing of the environment.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169886/1/geroskdj_1.pd

Intellectual Property Rights, Competition Policy and Innovation: Is There a Problem?

Paper presented by Geroski to the "IP, Competition and Human Rights" expert meeting held in 2004