Optimum spacings for the joint estimation and tests of hypothesis of location and scale parameters of the cauchy distribution

A simultaneous test for the location and scale parameters of the Cauchy distribution is considered based on selected order statistics.. It is shown that optimum spacings that maximise the Pitman ARE of the test coincide with that of the optimum spacings for the estimation problem.     

Migration and climate change: examining thresholds of change to guide effective adaptation decision-making

The implications of environmental change for migration are little understood. Migration as a response to climate change could be seen as a failure of in situ adaptation methods, or migration could be alternatively perceived as a rational component of creative adaptation to environmental risk. This paper frames migration as part of an adaptation response to climate change impacts to natural resource condition and environmental hazards. Thresholds will be reached by communities after which migration will become a vital component of an effective adaptation response. Such changes to migration patterns have the potential to undermine migration policy unless appropriate preparations are undertaken. This paper describes an approach to assist researchers to frame how climate change will influence migration by critically analysing how thresholds of fundamental change to migration patterns could be identified, primarily in relation to two case studies in Nepal and Thailand. Future policy for internal and international migration could be guided by the analysis of such thresholds of non-linear migration and resourced effectively to ensure that socio-economic and humanitarian outcomes are maximised.     

Exact confidence bounds for an exponential parameter under hybrid censoring

Consider a life testing experiment in which n units are put on test, successive failure times are recorded, and the observation is terminated either at a specified number r of failures or a specified time T whichever is reached first. This mixture of type I and type II censoring schemes, called hybrid censoring, is of wide use. Under this censoring scheme and the assumption of an exponential life distribution, the distribution of the maximum likelihood estimator of the mean life θ is derived. It is then used to construct an exact lower confidence bound for θ.     

Teaching and Learning Guide to Accompany Graffiti as a Form of Contentious Political Participation

The authors develop four exercises to further explore themes that are discussed in the Waldner and Dobratz article “Graffiti as a Form of Contentious Political Participation (Sociology Compass 7: 377–389),” including Mothers of the Plaza de Mayo (Madres de Plaza de Mayo), From Famous Political Speech (“Ich Bin Ein Berliner”) to Graffiti: “Ich bin Berliner”, “Protest, Violence, and Graffiti in Greek Politics,” and “Political Speech or Just Tagging: Billboards and Culture Jamming.” The authors encourage students to explore them such as motivations for graffiti, the difficulty in discerning writer intent, the use of graffiti as a form of political protest, and the historical and geographical context of graffiti. The authors provide links to YouTube videos and supplementary readings.     

HOME COMPUTERS AND EDUCATIONAL OUTCOMES: EVIDENCE FROM THE NLSY97 and CPS*

Although computers are universal in the classroom, nearly 20 million children in the United States do not have computers in their homes. Surprisingly, only a few previous studies explore the role of home computers in the educational process. Home computers might be very useful for completing school assignments, but they might also represent a distraction for teenagers. We use several identification strategies and panel data from the two main U.S. data sets that include recent information on computer ownership among children—the 2000–2003 Current Population Survey (CPS) Computer and Internet Use Supplements matched to the CPS basic monthly files and the National Longitudinal Survey of Youth 1997 (NLSY97)—to explore the causal relationship between computer ownership and high school graduation and other educational outcomes. Teenagers who have access to home computers are 6–8 percentage points more likely to graduate from high school than teenagers who do not have home computers after controlling for individual, parental, and family characteristics. We generally find evidence of positive relationships between home computers and educational outcomes using several identification strategies, including controlling for typically unobservable home environment and extracurricular activities in the NLSY97, fixed effects models, instrumental variables, and including future computer ownership and falsification tests. Home computers may increase high school graduation by reducing nonproductive activities, such as truancy and crime, among children in addition to making it easier to complete school assignments (JEL I2).     

On the number of separable partitions

Consider partitions of a given set A of n distinct points in general position in ℝ ^d into parts where each pair of parts can be separated by a hyperplane that contains a given set of points E. We consider the problem of counting and generating all such partitions (correcting a classic 1967 result of Harding about the number of such partitions into two parts). Applications of the result to partition problems are presented.     

On the asymptotic efficiency of moment and maximum likelihood estimators in the three-parameter inverse gaussian distribution

The asymptotic distribution of estimators generated by the methods of moments and maximum likelihood are considered. Simple formulae are provided which enable comparisons of asymptotic relative efficiency to be effected.