Kernel estimators for the second order parameter in extreme value statistics

We develop and study in the framework of Pareto-type distributions a general class of kernel estimators for the second order parameter ρ$\rho$, a parameter related to the rate of convergence of a sequence of linearly normalized maximum values towards its limit. Inspired by the kernel goodness-of-fit statistics introduced in Goegebeur et al. (2008), for which the mean of the normal limiting distribution is a function of ρ$\rho$, we construct estimators for ρ$\rho$ using ratios of ratios of differences of such goodness-of-fit statistics, involving different kernel functions as well as power transformations. The consistency of this class of ρ$\rho$ estimators is established under some mild regularity conditions on the kernel function, a second order condition on the tail function 1−F of the underlying model, and for suitably chosen intermediate order statistics. Asymptotic normality is achieved under a further condition on the tail function, the so-called third order condition. Two specific examples of kernel statistics are studied in greater depth, and their asymptotic behavior illustrated numerically. The finite sample properties are examined by means of a simulation study.     

Old and novel methods for estimating Feral Pigeons (Columba livia f. domestica) population size: a reply to Amoruso et al. (2013)

In a recent paper Amoruso et al. (2013) proposed a novel method for estimating population size of Feral Pigeons, the Superimposed Urban Strata (SUS) method. In our reply we firstly comment on the lack of a complete review of the available literature. Secondly we point out that the SUS method does not account for birds detection probability and thus it is just a simple index of abundance as many others proposed in recent years. Thirdly, we question the approach used by the authors to evaluate the reliability of their method. To conclude, we believe that the SUS method is not truly innovative and that further investigations are needed before considering it as a reliable way for estimating Feral Pigeons populations size.     

Neural Correlates of Pathological Gamblers Preference for Immediate Rewards During the Iowa Gambling Task: An fMRI Study

The Iowa Gambling Task (IGT) involves exploratory learning via rewards and penalties, where most advantageous task performance requires subjects to forego potential large immediate rewards for small longer-term rewards to avoid larger punishments. Pathological gambling (PG) subjects perform worse on the IGT compared to controls, relating to their persistence at high risk decisions involving the continued choice of potential large immediate rewards despite experiencing larger punishments. We wished to determine if neural processing of risk and reward within striatal and frontal cortex is associated with this behaviour observed in PG. Functional magnetic resonance imaging (fMRI) was used to assess brain activity in response to a computerized version of the IGT. Thirteen male PG subjects with no active comorbidities were compared to 13 demographically matched control subjects. In agreement with previous behavioural studies, PG subjects performed worse on the IGT and made more high-risk choices compared to controls, particularly after experiencing wins and losses. During high-risk gambling decisions, fMRI demonstrated that PG subjects exhibited relatively increased frontal lobe and basal ganglia activation, particularly involving the orbitofrontal cortex (OFC), caudate and amygdala. Increased activation of regions encompassing the extended reward pathway in PG subjects during high risk choices suggests that the persistence of PG may be due to the increased salience of immediate and greater potential monetary rewards relative to lower monetary rewards or potential future losses. Whether this over activation of the reward pathway is associated with the development of PG warrants further investigation.     

A local-influence-based diagnostic approach to a speeded item response theory model

Summary.  An item response theory model for dealing with omitted responses in a test is proposed. In this model formulation, non-response does not only depend on an examinee's ability and on item difficulty, but additionally also on 'test speededness'. Using a local-influence-based diagnostic approach, the sensitivity of the model regarding assumptions concerning the drop-out mechanism is explored. The methodology proposed is applied to the Chilean Sistema de Medición de la Calidad de la Educación mathematics test case-study.     

A Class of Non-parametric Tests in the Competing Risks Model for Comparing Two Samples

We consider a model when a process involving the production of elements is under inspection. The elements have possible failures due to competing risks. We assume the availability of a data set of failure times, D₁, obtained when the process is under control. Our main goal is to test if the failure rates in D₁ are equal to or less than the failure rates in another data set D₂, against "undesirable" neighbouring alternatives. A class of tests based on a two-dimensional vector statistic is obtained. Linear test statistics with weight functions giving optimal local asymptotic power are derived. Martingale techniques are used. An example illustrates the derivation of reasonable tests     

The Rayleigh–Lindley model: properties and applications

In this paper, the Rayleigh–Lindley (RL) distribution is introduced, obtained by compounding the Rayleigh and Lindley discrete distributions, where the compounding procedure follows an approach similar to the one previously studied by Adamidis and Loukas in some other contexts. The resulting distribution is a two-parameter model, which is competitive with other parsimonious models such as the gamma and Weibull distributions. We study some properties of this new model such as the moments and the mean residual life. The estimation was approached via EM algorithm. The behavior of these estimators was studied in finite samples through a simulation study. Finally, we report two real data illustrations in order to show the performance of the proposed model versus other common two-parameter models in the literature. The main conclusion is that the model proposed can be a valid alternative to other competing models well established in the literature.     

Possibilities and limitations of "lesbian continuum": the case of a protestant church in Japan

"Lesbian existence" is still invisible in Japanese society, although Japan is portrayed as being "tolerant" toward homosexuality. However, there is strong activism that tries to make lesbians visible. An example is Christian women's activism against homophobic discourses in the United Church of Christ in Japan (UCCJ/Kyodan) which is a denomination of Protestant Churches in Japan. This case helps us analyse the positionality of lesbians in the discourses of Christianity in a non-Christian society, Japan. Introduced to English-speaking audiences for the first time, this case shows clearly that the forces which produce the exclusion of lesbians and gays do not only have a religious origin but also a social background. This particular religious-social context sets the gay men as the object of discrimination but brings forth resistance activism by women-lesbians, bisexuals, and heterosexuals. Such women's activism against homophobia is analyzed as an example of the "lesbian continuum" (Adrienne Rich) and the possibilities and limitations of the continuum are explored. doi:10.1300/J155v10n03_10.