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Search Results: 1 - 10 of 3834 matches for " Rose Baker "
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Application of some new heavy-tailed survival distributions
Rose Baker
Statistics , 2014,
Abstract: Some new survival distributions are introduced based on a generalised exponential function. This class of distributions includes heavy-tailed generalisations of exponential, Weibull and gamma distributions. Properties of the distributions are described, and R code is available for computation of pdf, quantiles, inverse quantiles, random numbers, etc. A use of these distributions for robust inference is suggested, and this is exemplified with a Monte-Carlo study.
Copulas from Order Statistics
Rose Baker
Statistics , 2014,
Abstract: A new class of copulas based on order statistics was introduced by Baker (2008). Here, further properties of the bivariate and multivariate copulas are described, such as that of likelihood ratio dominance (LRD), and further bivariate copulas are introduced that generalize the earlier work. One of the new copulas is an integral of a product of Bessel functions of imaginary argument, and can attain the Fr\'echet bound. The use of these copulas for fitting data is described, and illustrated with examples. It was found empirically that the multivariate copulas previously proposed are not flexible enough to be generally useful in data fitting, and further development is needed in this area.
Properties and Applications of some Distributions derived from Frullani's integral
Rose Baker
Statistics , 2014,
Abstract: Frullani's integral dates from 1821, but a probabilistic interpretation of it has never been made. In this paper, Frullani's integral formula is shown to result from mixing a lifetime distribution by allowing the logarithm of the scale factor to be uniformly distributed over a finite range. This gives a class of long-tailed distributions related to slash distributions, where the pdf is simply expressed in terms of the survival function of the `parent' distribution. The resulting survival distributions have all moments finite, and can exhibit the bimodal hazard functions sometimes seen in practice. A distribution of this type analogous to the t-distribution is derived, the corresponding multivariate distributions are given, and two skewed versions of this distribution are derived. The use of the mixed distributions for inference is exemplified by fitting them to several datasets. It is expected that there will be many applications, in health, reliability, telecommunications, finance, etc.
A new distribution for robust least squares
Rose Baker,Dan Jackson
Statistics , 2014,
Abstract: A new distribution is introduced, which we call the twin-t distribution. This distribution is heavy-tailed like the t distribution, but closer to normality in the central part of the curve. Its properties are described, e.g. the pdf, the distribution function, moments, and random number generation. This distribution could have many applications, but here we focus on its use as an aid to robustness. We give examples of its application in robust regression and in curve fitting. Extensions such as skew and multivariate twin-t distributions, and a twin of
Bacterial Transfer from Hands While Eating Popcorn  [PDF]
Kimberly A. Baker, Inyee Y. Han, J. Bailey, Lauren Johnson, Edward Jones, Amy Knight, Mollye MacNaughton, Peter Marvin, Katherine Nolan, Rose Martinez-Dawson, Paul L. Dawson
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.615139
Abstract: Popcorn is a very social food, often shared with others and offered at many major sporting events, concerts, movies, and fairs. However, sharing may not be safe since microorganisms found on hands may be transferred onto the shared popcorn. This study was conducted to determine if bacteria are transferred from hands to popcorn during handling. Over 30 samplings revealed that bacterial transfer to popcorn from hands was very low; however transfer did occur with large variation between subjects. Since hands and surfaces can carry bacteria in situations where food is being shared, transferring bacteria from one person to another person is always a risk.
Endogenous Ranking in the Two-Sector Urn-Ball Matching Process  [PDF]
Giuseppe Rose
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.83024
Abstract: This paper contributes to the debate concerning micro-foundations of matching functions in frictional labor markets. The focus is on a particular matching regime, i.e., the so-called urn-ball process. It is shown that in a twosector economy, even in the presence of heterogeneous workers, the assumption of applicants-ranking may be misleading. Instead, the choice concerning the adoption of either ranking or no-ranking behavior is endogenous and it is affected by both the tightness of the two sectors and the composition of the labor force in terms of skills. Moreover it is proved that exogenous shocks may change the form of the matching function. This result casts additional doubts on the assumption of exogenous matching function often made in empirical works aimed at assessing the effectiveness of policy measures.
Sparse Representation by Frames with Signal Analysis  [PDF]
Christopher Baker
Journal of Signal and Information Processing (JSIP) , 2016, DOI: 10.4236/jsip.2016.71006
Abstract: The use of frames is analyzed in Compressed Sensing (CS) through proofs and experiments. First, a new generalized Dictionary-Restricted Isometry Property (D-RIP) sparsity bound constant for CS is established. Second, experiments with a tight frame to analyze sparsity and reconstruction quality using several signal and image types are shown. The constant \"\"?is used in fulfilling the definition of D-RIP. It is proved that k-sparse signals can be reconstructed if \"\"?by using a concise and transparent argument1. The approach could be extended to obtain other D-RIP bounds (i.e. \"\"). Experiments contrast results of a Gabor tight frame with Total Variation minimization. In cases of practical interest, the use of a Gabor dictionary performs well when achieving a highly sparse representation and poorly when this sparsity is not achieved.
CD4 Cell Counts at HIV Diagnosis among HIV Outpatient Study Participants, 2000–2009
Kate Buchacz,Carl Armon,Frank J. Palella,Rose K. Baker,Ellen Tedaldi,Marcus D. Durham,John T. Brooks
AIDS Research and Treatment , 2012, DOI: 10.1155/2012/869841
Abstract: Background. It is unclear if CD4 cell counts at HIV diagnosis have improved over a 10-year period of expanded HIV testing in the USA. Methods. We studied HOPS participants diagnosed with HIV infection ≤6 months prior to entry into care during 2000–2009. We assessed the correlates of CD4 count <200 cells/mm3 at HIV diagnosis (late HIV diagnosis) by logistic regression. Results. Of 1,203 eligible patients, 936 (78%) had a CD4 count within 3 months after HIV diagnosis. Median CD4 count at HIV diagnosis was 299 cells/mm3 and did not significantly improve over time ( ). Comparing periods 2000-2001 versus 2008-2009, respectively, 39% and 35% of patients had a late HIV diagnosis ( ). Independent correlates of late HIV diagnosis were having an HIV risk other than being MSM, age ≥35 years at diagnosis, and being of nonwhite race/ethnicity. Conclusions. There is need for routine universal HIV testing to reduce the frequency of late HIV diagnosis and increase opportunity for patient- and potentially population-level benefits associated with early antiretroviral treatment. 1. Introduction Recent HIV surveillance data suggest that approximately 33% of HIV-infected persons in the United States present for HIV testing late and have AIDS (CD4+ cell count <200?cells/mL or an AIDS-defining illness) within one year after HIV diagnosis [1, 2]. Patients are less likely to experience the full benefits of highly active combination antiretroviral (cART) therapy if they enter HIV care and initiate treatment at a CD4 count <350?cells/mm3 [3, 4]; the clinical cost is even more profound when the CD4 count is <200?cells/mm3 or the patient has already developed clinical AIDS [5–8]. In addition, persons who remain unaware of their HIV-positive status (estimated 21% to 25% of infected persons in the USA in recent years) [9, 10] may not only miss the benefits of earlier cART treatment, but are also more likely to remain chronically viremic and are thereby more likely to transmit HIV to their sexual and needle-sharing partners [9]. The CDC has been promoting strategies to encourage more widespread HIV screening to diagnose infected persons earlier in the course of their illness, including by releasing in 2006 the guidelines for implementing routine universal opt-out testing in healthcare settings [11]. Yet, the latest HIV surveillance data [1, 2] and epidemiologic studies in multiple US populations indicate that the proportion of persons who are diagnosed late in the course of HIV infection [2, 12, 13] or present late for HIV care [14, 15] remains unacceptably high. Stable or worsening
Using ordinal logistic regression to evaluate the performance of laser-Doppler predictions of burn-healing time
Rose D Baker, Christian Weinand, James C Jeng, Henk Hoeksema, Stan Monstrey, Sarah A Pape, Robert Spence, David Wilson
BMC Medical Research Methodology , 2009, DOI: 10.1186/1471-2288-9-11
Abstract: We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool.Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA), site and cause of burn, day of LDI scan, burn center). It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small.Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for.The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the perce
Newspaper Reports on BSE around the Time of the Japan-US Trade Conflicts: Content Analysis of Japanese and US Dailies from 2002 to 2006  [PDF]
Hajime Sato, Rose G. Rose G. Campbell
Advances in Journalism and Communication (AJC) , 2014, DOI: 10.4236/ajc.2014.21003
Abstract: Mass media can affect how people understand and react to particular health risks. Reporting of health risks during the international trade disputes, resulting from the difference in safety regulations, therefore can play a pivotal role in resolving them. This study compared the newspaper reports on BSE-related events in major national dailies between Japan and the US around the period when BSE-infected cattle were discovered in the US and the import of US beef products was banned (between December 2002 and November 2006). During the study period, the number of BSE-related newspaper articles increased in both the US and Japan, but the visibility of the issue was more prominent and persistent in Japan than in the US. Geographically, most of the articles had a domestic focus, but they also reported the news of each trade partner. After the discovery of BSE cattle in the US, articles of commerce and trade issues were dominant in Japan, while the incidence of BSE, agriculture, and trade dominated in the US. Overall, the US-based newspapers carried more advocacy articles than the Japanese ones. In Japan, calls for stronger domestic policy decreased, but those for stronger foreign policy increased slightly. Meanwhile, in the US, calls for a stronger domestic policy increased slightly whereas those for weaker foreign policy dropped-both only temporarily. The major rationale for policy advocacy was the economy and health in both Japan and the US. However, the balance of competing policy objectives and the rational acceptance of BSE risks were argued more in the US papers than in the Japanese ones. In conclusion, during the BSE-related dispute on health and trade, the visibility and faces of the issues in newspapers differed between Japan and the US. Acceptance of BSE-related risks was argued differently, and those differences reflected and affected the public's perception of BSE issues, the related safety policies by the governments, and the configuration of social interests in each country. The differences evident in the media could serve as a vehicle for reappraising the existing policies as well as the possible international harmonization of risk management policies.
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