Relative errors for bootstrap approximations of the serial correlation coefficient

We consider the first serial correlation coefficient under an AR(1) model where errors are not assumed to be Gaussian. In this case it is necessary to consider bootstrap approximations for tests based on the statistic since the distribution of errors is unknown. We obtain saddle-point approximations for tail probabilities of the statistic and its bootstrap version and use these to show that the bootstrap tail probabilities approximate the true values with given relative errors, thus extending the classical results of Daniels [Biometrika 43 (1956) 169-185] for the Gaussian case. The methods require conditioning on the set of odd numbered observations and suggest a conditional bootstrap which we show has similar relative error properties.Comment: Published in at http://dx.doi.org/10.1214/13-AOS1111 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

An fMRI study of parietal cortex involvement in the visual guidance of locomotion

Locomoting through the environment typically involves anticipating impending changes in heading trajectory in addition to maintaining the current direction of travel. We explored the neural systems involved in the “far road” and “near road” mechanisms proposed by Land and Horwood (1995) using simulated forward or backward travel where participants were required to gauge their current direction of travel (rather than directly control it). During forward egomotion, the distant road edges provided future path information, which participants used to improve their heading judgments. During backward egomotion, the road edges did not enhance performance because they no longer provided prospective information. This behavioral dissociation was reflected at the neural level, where only simulated forward travel increased activation in a region of the superior parietal lobe and the medial intraparietal sulcus. Providing only near road information during a forward heading judgment task resulted in activation in the motion complex. We propose a complementary role for the posterior parietal cortex and motion complex in detecting future path information and maintaining current lane positioning, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved

A time for learning: representations of time and the temporal dimensions of learning through the lifecourse

Based on findings from a large-scale longitudinal study into the learning biographies of adults, this paper focuses on the different representations of time in the interview data. The paper discusses three such representations: chronological time, narrative time, and generational time. The authors show how different notions of time operate within the construction of life stories. They also analyse the ways in which different representations of time impact upon and serve as resources for reflection on and learning from life, thus contributing to understanding the complex relationships between biography, life and time. (DIPF/Orig.)

Masters' courses in the education of adults in the UK

This is a paper from the Academic Papers Online series from ESCalate, written by John Field, Richard Dockrell, Peter Gray in 2005. Universities provide a range of advanced qualifications for professionals who support adult learners. Describing and evaluating this body of work, though, poses something of a challenge. The field of continuing education is a broad one, which has been widened further by current government policies promoting lifelong learning, as well as by increased concerns for quality improvement among providers in further and higher education. Qualifications are accordingly offered under a variety of different titles: many universities now offer taught postgraduate courses in areas such as lifelong learning, continuing education, post-compulsory education and training or adult education. This report examines the background against which these courses developed, and explores a number of curricular and organisational issues associated with them. It includes, as an appendix, a list of courses currently offered in British higher education institution

Beyond foraging: behavioral science and the future of institutional economics

Institutions affect economic outcomes, but variation in them cannot be directly linked to environmental factors such as geography, climate, or technological availabilities. Game theoretic approaches, based as they typically are on foraging only assumptions, do not provide an adequate foundation for understanding the intervening role of politics and ideology; nor does the view that culture and institutions are entirely socially constructed. Understanding what institutions are and how they influence behavior requires an approach that is in part biological, focusing on cognitive and behavioral adaptations for social interaction favored in the past by group selection. These adaptations, along with their effects on canalizing social learning, help to explain uniformities in political and social order, and are the bedrock upon which we build cultural and institutional variability

Feedback on Academic Essay Writing through pre-Emptive Hints: Moving Towards "Advice for Action"

This paper adopts an “advice for action” approach to feedback in educational practice: addressing how provision of “hints” to participants before they write academic essays can support their understanding and performance in essay-writing tasks. We explored differences in performance by type of hint, and whether there was a transfer of better performance in subsequent essays. Fifty participants were recruited, consisting of eight men and 42 women aged 18-80. Participants were assigned in rotation to four groups, and asked to write two essays. Groups 1 and 3 received hints before Essay 1, whilst Groups 2 and 4 received hints before Essay 2. Groups 1 and 2 received essential hints; Groups 3 and 4 received helpful hints. Essays were marked against set criteria. The results showed that an “advice for action” approach to essay-writing, in the form of hints, can significantly improve writers’ marks. Specifically higher marks were gained for the introduction, conclusion and use of evidence: critical components of “good” academic essays. As the hints given were content-free, this approach has the potential to instantly benefit tutors and students across subject domains and institutions and is informing the development of a technical system that can offer formative feedback as students draft essays

On the Production of Homeland Security Under True Uncertainty

Homeland security against possible terrorist attacks involves making decisions under true uncertainty. Not only are we ignorant of the form, place, and time of potential terrorist attacks, we are also largely ignorant of the likelihood of these attacks. In this paper, we conceptualize homeland security under true uncertainty as society’s immunity to unacceptable losses. We illustrate and analyze the consequences of this notion of security with a simple model of allocating a fixed budget for homeland security to defending the pathways through which a terrorist may launch an attack and to mitigating the damage from an attack that evades this defense. In this problem, immunity is the range of uncertainty about the likelihood of an attack within which the actual expected loss will not exceed some critical value. We analyze the allocation of a fixed homeland security budget to defensive and mitigative efforts to maximize immunity to alternative levels of expected loss. We show that the production of homeland security involves a fundamental trade-off between immunity and acceptable loss; that is, for fixed resources that are optimally allocated to defense and mitigation, increasing immunity requires accepting higher expected losses, and reducing acceptable expected losses requires lower immunity. Greater investments in homeland security allow society to increase its immunity to a particular expected loss, reduce the expected losses to which we are immune while holding the degree of immunity constant, or some combination of increased immunity to a lower critical expected loss.Homeland Security, Terrorism, True Uncertainty

What does the occurrence of Sporormiella (Preussia) spores mean in Australian fossil sequences?

Understanding the loss of the final few species of Australian megafauna is beset by a paucity of data on human arrival, well-provenanced megafauna, human/megafauna population range and distribution (coexistence and interaction), and the range, scale and impact of environmental changes spanning the human-megafauna period. To overcome these shortcomings, the occurrence and decline of coprophilous fungal spores of Sporormiella in sediments have been used as a proxy for extinct megaherbivores. The Sporormiella evidence is presented as the key indicator of extinction timing and these reports are often from locations where there is no known archaeological record or megafauna remains. However, interpreting fungal spore occurrence is not straightforward, as demonstrated by studies investigating taphonomy, taxonomy and the types of animal dung where Sporormiella occurs. No detailed studies on these problems exist for Australia and no evidence supporting the use of Sporormiella as a valid proxy has been reported. Here we examine the occurrence of Sporormiella spores from Cuddie Springs in south-eastern Australia. Despite a well-preserved suite of megafauna fossils, Sporormiella occurrence is sporadic and frequencies are low. We conclude that using Sporormiella alone as an indicator for the presence of megafauna is premature for the Australian context. Copyright (C) 2018 John Wiley & Sons, Ltd