New York University

About: New York University is a education organization based out in New York, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 72380 authors who have published 165545 publications receiving 8334030 citations. The organization is also known as: NYU & University of the City of New York.

emcee: The MCMC Hammer

Abstract: We introduce a stable, well tested Python implementation of the affine-invariant ensemble sampler for Markov chain Monte Carlo (MCMC) proposed by Goodman & Weare (2010). The code is open source and has already been used in several published projects in the astrophysics literature. The algorithm behind emcee has several advantages over traditional MCMC sampling methods and it has excellent performance as measured by the autocorrelation time (or function calls per independent sample). One major advantage of the algorithm is that it requires hand-tuning of only 1 or 2 parameters compared to $\sim N^2$ for a traditional algorithm in an N-dimensional parameter space. In this document, we describe the algorithm and the details of our implementation and API. Exploiting the parallelism of the ensemble method, emcee permits any user to take advantage of multiple CPU cores without extra effort. The code is available online at this http URL under the MIT License.

Understanding Interaction Models: Improving Empirical Analyses

Abstract: Multiplicative interaction models are common in the quantitative political science literature. This is so for good reason. Institutional arguments frequently imply that the relationship between political inputs and outcomes varies depending on the institutional context. Models of strategic interaction typically produce conditional hypotheses as well. Although conditional hypotheses are ubiquitous in political science and multiplicative interaction models have been found to capture their intuition quite well, a survey of the top three political science journals from 1998 to 2002 suggests that the execution of these models is often flawed and inferential errors are common. We believe that considerable progress in our understanding of the political world can occur if scholars follow the simple checklist of dos and don'ts for using multiplicative interaction models presented in this article. Only 10% of the articles in our survey followed the checklist.

Reporting structural equation modeling and confirmatory factor analysis results: A review

Abstract: The authors provide a basic set of guidelines and recommendations for information that should be included in any manuscript that has confirmatory factor analysis or structural equation modeling as the primary statistical analysis technique. The authors provide an introduction to both techniques, along with sample analyses, recommendations for reporting, evaluation of articles in The Journal of Educational Research using these techniques, and concluding remarks.

Competition and Entrepreneurship

Abstract: Kirzner, writing from a neo-Austrian economic perspective that is inherently dynamic with an emphasis on action over time, offers a critique of the prevailing positivistic, value freedom of orthodox microeconomics and price theory, focusing on what he believes is its unrealistic emphasis on static equilibrium analysis. Kirzner criticizes the methodology of Robbinsian equililbrium analysis in which a competitive market is a situation in which buyers and sellers have perfect knowledge and in which decision-making is mechanical and its solutions given. This analysis, according to Kirzner, eliminates all consideration of the competitive process and of entrepreneurship (which is synonymous, for him, with competitive activity); the assumption of perfect knowledge is unrealistic. He offers a full elaboration of the Mises-Hayek view of entrepreneurship and competition as a process based on von Mises' idea of "human action" rather than Marshall's idea of economizing. Kirzner sees the entrepreneur as always alert to information and propelling the system forward by seeking out price discrepancies as opportunities for profit. This process depends not on impulses from technology or genius; rather every market participant is a potential entrepreneur who can exploit a situation, which depends on a lack of perfect knowledge among the market participants. Entrepreneurial activity is always competitive; and competitive activity is always entrepreneurial. Kirzner is thus also a critique of the Schumpeterian view of entrepreneurship as disrupter of equilibrium; rather the entrepreneur removes disequilibrium in a short-run movement to an equilibrium position. A Kirznerian entrepreneur is a decision-maker whose entire role arises from alertness to unnoticed opportunities or knowledge about market data. Within the context of entrepreneurial activity, he offers a neo-Austrian redefinition of the concept of monopoly and competition. Since for Kirzner entrepreneurship involves no element of resource ownership, monopoly is defined as the impact of input ownership on the competitive process, and not the shape of the demand curve facing a firm. A monopoly position can be won by an alert entrepreneur. In the light of his theory of competition, Kirzner provides a new theoretical place for advertising and selling costs. Advertising, which promotes and calls attention to product differentiation, is the "weapon" of competition, which allows competitive-entrepreneurial adjustments in the type of products placed in the market in disequilibrium. Kirzner's revaluation of advertising is thus opposed to the idea of advertising as a social waste. Kirzner also offers a new conception of economic welfare based on the "coordination-of-knowledge-and-actions" instead of the orthodox "allocation of social resources" standard. (TNM)