Using geotagged tweets to track population movements to and from Puerto Rico after Hurricane Maria

Population and Environment - After a disaster, there is an urgent need for information on population mobility. Our analysis examines the suitability of Twitter data for measuring post-disaster...     

Testing for Causal Effects in a Generalized Regression Model With Endogenous Regressors

A unifying framework to test for causal effects in nonlinear models is proposed. We consider a generalized linear‐index regression model with endogenous regressors and no parametric assumptions on the error disturbances. To test the significance of the effect of an endogenous regressor, we propose a statistic that is a kernel‐weighted version of the rank correlation statistic (tau) of Kendall (1938). The semiparametric model encompasses previous cases considered in the literature (continuous endogenous regressors (Blundell and Powell (2003)) and a single binary endogenous regressor (Vytlacil and Yildiz (2007))), but the testing approach is the first to allow for (i) multiple discrete endogenous regressors, (ii) endogenous regressors that are neither discrete nor continuous (e.g., a censored variable), and (iii) an arbitrary “mix” of endogenous regressors (e.g., one binary regressor and one continuous regressor).     

The Impact of Forecast Errors on Early Order Commitment in a Supply Chain*

Supply chain partnership involves mutual commitments among participating firms. One example is early order commitment, wherein a retailer commits to purchase a fixed‐order quantity and delivery time from a supplier before the real need takes place. This paper explores the value of practicing early order commitment in the supply chain. We investigate the complex interactions between early order commitment and forecast errors by simulating a supply chain with one capacitated supplier and multiple retailers under demand uncertainty. We found that practicing early order commitment can generate significant savings in the supply chain, but the benefits are only valid within a range of order commitment periods. Different components of forecast errors have different cost implications to the supplier and the retailers. The presence of trend in the demand increases the total supply chain cost, but makes early order commitment more appealing. The more retailers sharing the same supplier, the more valuable for the supply chain to practice early order commitment. Except in cases where little capacity cushion is available, our findings are relatively consistent in the environments where cost structure, number of retailers, capacity utilization, and capacity policy are varied.     

Covariates and Random Effects in a Gamma Process Model with Application to Degradation and Failure

The gamma process is a natural model for degradation processes in which deterioration is supposed to take place gradually over time in a sequence of tiny increments. When units or individuals are observed over time it is often apparent that they degrade at different rates, even though no differences in treatment or environment are present. Thus, in applying gamma-process models to such data, it is necessary to allow for such unexplained differences. In the present paper this is accomplished by constructing a tractable gamma-process model incorporating a random effect. The model is fitted to some data on crack growth and corresponding goodness-of-fit tests are carried out. Prediction calculations for failure times defined in terms of degradation level passages are developed and illustrated.     

Risk return approach to product portfolio strategy

This article describes how a risk-return portfolio analysis, as originally developed in economics and finance, can be applied to product-line decisions. This approach uses direct estimates of return, and explicitly considers risk, or variation in return; most of the product portfolio models in use today forecast return by correlation, and lack explicit treatment of risk. The approach provides guidance for new product development activities as well as for allocating resources among a corporation's existing product lines. The article explains how organizations can apply this approach to their own product portfolio decisions, and includes a detailed example of how one company used this model.     

The De/Repoliticization of Cooperation and the Discourse of Conversion1

Abstract In recent years, several agricultural cooperatives have undergone significant restructuring. Some have been taken through a conversion process and have been reorganized as “investor-oriented firms” (IOFs). This phenomenon has attracted the interest of agricultural economists, but it has not been analyzed by sociologists. This article examines the discourse with which agricultural economists have approached the conversion issue. Drawing upon Fraser's discussion of “needs talk,” and inspired by Kloppenburg's analysis of the agricultural scientific complex, an argument is made that a reprivatization discourse of neoclassical economics has effectively depoliticized discussion about the future of cooperative enterprise. It is further argued that a repoliticization of cooperation is necessary in order to assure the protection of extra-economic values and oppositional discourse that is embedded in the historical development of cooperative practices and institutions. We focus here on the role of expert discourse as it relates to the reinvention of cooperative institutions in the agricultural economy. It is argued that this discourse would be improved by greater attention to historical and sociological forces, rather than remaining narrowly focused on economism.     

Factors in the Post-Stalin Emergence of Soviet Sociology*

This paper attempts to analyze the social, economic, and political sources for the emergence of modern Soviet sociology in the 1950s. While it does not address extensively the characteristics of current Soviet sociology, it is suggested that those characteristics of a methodologically sophisticated and economically oriented sociology are largely the result of a compact between Soviet leaders and sociologists which allowed and required its post-Stalin emergence. Four sets of factors are evaluated in terms of their effect on the emergence of Soviet sociology. These are 1) the Marxist-Leninist vision (that is, the Utopian elements of ideology), 2) the Soviet ideology (that is, the elements of ideology oriented toward system maintenance), 3) the diffusion of ideas, and 4) the mandate of Soviet economic development. A brief evaluation of these sets of factors as they affect the emergence of Chinese sociology in the early 1980s is also provided. It is concluded that the future shape of sociology in the USSR and China is dependent upon the evolution of ideology in the two countries, an evolution that is intimately tied to the succession of political leadership.     

The queer sensitive interveners in the Little Sisters case: a response to Dr. Kendall

Three queer sensitive organizations intervened before the Supreme Court of Canada in Little Sisters v. Canada, a case that challenged whether and how Canada Customs treated cross border shipments to a gay and lesbian bookstore. This paper reviews the queer sensitive organizations' arguments on some of the issues in the case, especially the scope of obscenity law, and challenges misconceptions about their positions, including those presented in Dr. Kendall's paper (appearing in this volume).