16,907 research outputs found
Bayesian astrostatistics: a backward look to the future
This perspective chapter briefly surveys: (1) past growth in the use of
Bayesian methods in astrophysics; (2) current misconceptions about both
frequentist and Bayesian statistical inference that hinder wider adoption of
Bayesian methods by astronomers; and (3) multilevel (hierarchical) Bayesian
modeling as a major future direction for research in Bayesian astrostatistics,
exemplified in part by presentations at the first ISI invited session on
astrostatistics, commemorated in this volume. It closes with an intentionally
provocative recommendation for astronomical survey data reporting, motivated by
the multilevel Bayesian perspective on modeling cosmic populations: that
astronomers cease producing catalogs of estimated fluxes and other source
properties from surveys. Instead, summaries of likelihood functions (or
marginal likelihood functions) for source properties should be reported (not
posterior probability density functions), including nontrivial summaries (not
simply upper limits) for candidate objects that do not pass traditional
detection thresholds.Comment: 27 pp, 4 figures. A lightly revised version of a chapter in
"Astrostatistical Challenges for the New Astronomy" (Joseph M. Hilbe, ed.,
Springer, New York, forthcoming in 2012), the inaugural volume for the
Springer Series in Astrostatistics. Version 2 has minor clarifications and an
additional referenc
Photoproduction at low Q^2
The past year has seen a number of important developments in hard
photoproduction physics at the HERA Collider. These are surveyed.Comment: 16 pages, 13 figures. Talk given at 19th Physics in Collision
conference, Ann Arbor, USA, June 199
Nurturing Breakthroughs: Lessons from Complexity Theory
A general theory of innovation and progress in human society is outlined,
based on the combat between two opposite forces (conservatism/inertia and
speculative herding "bubble" behavior). We contend that human affairs are
characterized by ubiquitous ``bubbles'', which involve huge risks which would
not otherwise be taken using standard cost/benefit analysis. Bubbles result
from self-reinforcing positive feedbacks. This leads to explore uncharted
territories and niches whose rare successes lead to extraordinary discoveries
and provide the base for the observed accelerating development of technology
and of the economy. But the returns are very heterogeneous, very risky and may
not occur. In other words, bubbles, which are characteristic definitions of
human activity, allow huge risks to get huge returns over large scales. We
outline some underlying mathematical structure and a few results involving
positive feedbacks, emergence, heavy-tailed power laws, outliers/kings/black
swans, the problem of predictability and the illusion of control, as well as
some policy implications.Comment: 14 pages, Invited talk at the workshop Trans-disciplinary Research
Agenda for Societal Dynamics (http://www.uni-lj.si/trasd in Ljubljana),
organized by J. Rogers Hollingsworth, Karl H. Mueller, Ivan Svetlik, 24 - 25
May 2007, Ljubljana, Sloveni
Memories of Murray and the Quark Model
Life at Caltech with Murray Gell-Mann in the early 1960's is remembered. Our
different paths to quarks, leading to different views of their reality, are
described.Comment: Talk presented at the "Conference in Honor of Murray Gell-Mann's 80th
Birthday," Nanyang Technical University, Singapore, February 24,2010. 18
pages, 4 figure
Coordination, Division of Labor, and Open Content Communities: Template Messages in Wiki-Based Collections
In this paper we investigate how in commons based peer production a large community of contributors coordinates its efforts towards the production of high quality open content. We carry out our empirical analysis at the level of articles and focus on the dynamics surrounding their production. That is, we focus on the continuous process of revision and update due to the spontaneous and largely uncoordinated sequence of contributions by a multiplicity of individuals. We argue that this loosely regulated process, according to which any user can make changes to any entry, while allowing highly creative contributions, has to come into terms with potential issues with respect to the quality and consistency of the output. In this respect, we focus on emergent, bottom up organizational practice arising within the Wikipedia community, namely the use of template messages, which seems to act as an effective and parsimonious coordination device in emphasizing quality concerns (in terms of accuracy, consistency, completeness, fragmentation, and so on) or in highlighting the existence of other particular issues which are to be addressed. We focus on the template "NPOV" which signals breaches on the fundamental policy of neutrality of Wikipedia articles and we show how and to what extent imposing such template on a page affects the production process and changes the nature and division of labor among participants. We find that intensity of editing increases immediately after the "NPOV" template appears. Moreover, articles that are treated most successfully, in the sense that "NPOV" disappears again relatively soon, are those articles which receive the attention of a limited group of editors. In this dimension at least the distribution of tasks in Wikipedia looks quite similar to what is know about the distribution in the FLOSS development process
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