The Effectiveness of Categorical Variables in Discriminant Function Analysis

A preliminary study of the feasibility of using categorical variables in discriminant function analysis was performed. Data including both continuous and categorical variables were used and predictive results examined. The discriminant function techniques were found to be robust enough to include the use of categorical variables. Some problems were encountered with using the trace criterion for selecting the most discriminating variables when these variables are categorical. No monotonic relationship was found to exist between the trace and the number of correct predictions. This study did show that the use of categorical variables does have much potential as a statistical tool in classification procedures. (50 pages

Assessment of efforts to reduce nonresponse bias: 1996 Survey of Income and Program Participation (SIPP)

Im Vorfeld der neuen Welle des SIPP 1996 tauchten Bedenken in Hinblick auf eine zunehmende Tendenz zur Antwortverweigerung in den Panelwellen der Jahre 1991 bis 1993 auf. Gleichzeitig wurde die Existenz eines Bias in den SIPP-Zeitreihenschätzungen zu Armut bekannt. Das US Census Bureau hat viel Zeit und Geld darauf verwandt, den Anteil der Antwortverweigerung zu reduzieren und die hierauf beruhende Fehlgewichtung zu korrigieren. Die Verfasser geben einen Überblick über diese Maßnahmen und diskutieren deren Wirksamkeit mit Blick auf das erste Jahr der Panelwelle 1996. Sie setzen sich mit dem Einsatz finanzieller Anreize, der Durchführung von Untersuchungen zur Antwortverweigerung sowie Veränderungen in der Durchführung der Feldforschung auseinander. (ICEÜbers)"Concern over increasing levels of nonresponse in the 1991-1993 SIPP Panels and new information about the existence of bias in time series estimates of poverty front the SIPP surfaced prior to fielding the newly redesigned SIPP 1996 sample. A tremendous amount of effort and expense has been dedicated by the U.S. Census Bureau to reducing nonresponse and adjusting for its bias. This paper will summarize these efforts and provide a preliminary assessment of the success of the efforts for the first year of the 1996 panel. The authors will discuss the use of monetary incentives, fielding nonresponse surveys, and changes in field staffing and procedures." (author's abstract

Towards a Best Practice for Developing Best Practices in Ocean Observation (BP4BP): Supporting Methodological Evolution through Actionable Documentation

IOC Manuals and Guides, 84 Abstract Ever-increasing complexity and multi-dimensionality of ocean investigations present a challenge for the ocean community as we collaboratively (co-)develop methods to research, monitor, and use our oceans. To support transparent sharing of methods, and ultimately agree on best practices in ocean research, operations, and application, the IOC Ocean Best Practices System (OBPS) was initially developed as an Ocean Data Standards project deliverable of the International Oceanographic Data Exchange (IODE) who in 2017 joined with the AtlantOS/ODIP/RCN Best Practices Working Group (BPWG) to develop it into a System. In 2019 the IOC Ocean Best Practices System was approved as a UNESCO/Intergovernmental Oceanographic Commission (IOC) Project, jointly funded by the IODE and GOOS Programmes. In this document, we provide guidance on how to best use the OBPS templates, allowing greater discovery, machine readability, sharing, and understandability of methods and best practices. We clarify how to optimally populate the different sections of an OBPS template, and describe how those sections support the evolution of each OBPS submission, towards a global best practice. Further, we discuss some general challenges in developing methods into community-accepted best practices. While this document focuses on the OBPS, it also offers a perspective on the general challenge of structuring and harmonising method documentation. We invite the community to provide feedback on this document (link to Community review), to contribute towards a generalised best practice for advanced methodological management across the ocean community

Submission 238 to: Australia's Science and Research Priorities - Conversation Starter

Australia plans to obtain, build, and operate nuclear propelled submarines. The immense challenges brought about by this change in national defence strategy, along with the ambition to create a 20,000 strong nuclear science and engineering capable workforce, must be reflected in the National Science and Research Priorities, and the National Science Statement. We therefore recommend the inclusion of Nuclear Technology as a contemporary National Science and Research Priority, for consideration by the Science Strategy and Priorities Taskforce

Foreign Exchange Rate and Economic Growth: The Case of Hong Kong

The relationship between the exchange rate and the real GDP of Hong Kong in the long period from 1955 to 2015 is investigated using a structural VAR model. The mutual effect of the two variables is studied in three periods: The results indicate that there is no obvious relationship between the exchange rate and real GDP before Hong Kong’s economy booming. However, a significant positive correlation is found in the sample of 1975–1998, which is associated with the output increases. The direction between the exchange rate and real GDP becomes negative after 1998. In addition, based on Granger causality test, we found the exchange rate could Granger causes GDP after 1975, but there is no Granger causality connection between the two variables before 1975

A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope

Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gamma-ray emission. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular clusters. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices $(0.7 < \Gamma <1.4)$ and clear evidence for an exponential cut-off in the range 1.0-2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices $(1.0 < \Gamma < 1.7)$, however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600-4700 MSPs in Galactic globular clusters, commensurate with previous estimates. The observation of high-energy gamma-ray emission from a globular cluster thus provides a reliable independent method to assess their millisecond pulsar populations that can be used to make constraints on the original neutron star X-ray binary population, essential for understanding the importance of binary systems in slowing the inevitable core collapse of globular clusters.Comment: Accepted for publication in A&A. Corresponding authors: J. Kn\"odlseder, N. Webb, B. Pancraz

Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

Distribution and Habitat Associations of Billfish and Swordfish Larvae across Mesoscale Features in the Gulf of Mexico

Ichthyoplankton surveys were conducted in surface waters of the northern Gulf of Mexico (NGoM) over a three-year period (2006–2008) to determine the relative value of this region as early life habitat of sailfish (Istiophorus platypterus), blue marlin (Makaira nigricans), white marlin (Kajikia albida), and swordfish (Xiphias gladius). Sailfish were the dominant billfish collected in summer surveys, and larvae were present at 37.5% of the stations sampled. Blue marlin and white marlin larvae were present at 25.0% and 4.6% of the stations sampled, respectively, while swordfish occurred at 17.2% of the stations. Areas of peak production were detected and maximum density estimates for sailfish (22.09 larvae 1000 m−2) were significantly higher than the three other species: blue marlin (9.62 larvae 1000 m−2), white marlin (5.44 larvae 1000 m−2), and swordfish (4.67 larvae 1000 m−2). The distribution and abundance of billfish and swordfish larvae varied spatially and temporally, and several environmental variables (sea surface temperature, salinity, sea surface height, distance to the Loop Current, current velocity, water depth, and Sargassum biomass) were deemed to be influential variables in generalized additive models (GAMs). Mesoscale features in the NGoM affected the distribution and abundance of billfish and swordfish larvae, with densities typically higher in frontal zones or areas proximal to the Loop Current. Habitat suitability of all four species was strongly linked to physicochemical attributes of the water masses they inhabited, and observed abundance was higher in slope waters with lower sea surface temperature and higher salinity. Our results highlight the value of the NGoM as early life habitat of billfishes and swordfish, and represent valuable baseline data for evaluating anthropogenic effects (i.e., Deepwater Horizon oil spill) on the Atlantic billfish and swordfish populations

Movements and Population Structure of Humpback Whales in the North Pacific

Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan) each with two to three subareas, and feeding areas that extended from southern California to the Aleutian Islands. Of the 6,413 identification photographs of humpback whales obtained by 16 independent research groups between 1990 and 1993 and examined for this study, 3,650 photographs were determined to be of suitable quality. A total of 1,241 matches was found by two independent matching teams, identifying 2,712 unique whales in the sample (seen one to five times). Site fidelity was greatest at feeding areas where there was a high rate of resightings in the same area in different years and a low rate of interchange among different areas. Migrations between winter regions and feeding areas did not follow a simple pattern, although highest match rates were found for whales that moved between Hawaii and southeastern Alaska, and between mainland and Baja Mexico and California. Interchange among subareas of the three primary wintering regions was extensive for Hawaii, variable (depending on subareas) for Mexico, and low for Japan and reflected the relative distances among subareas. Interchange among these primary wintering regions was rare. This study provides the first quantitative assessment of the migratory structure of humpback whales in the entire North Pacific basin