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Binomial Models (binomial + models)
Kinds of Binomial Models Selected AbstractsBinomial Models in FinanceJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2008Jordan Stoyanov No abstract is available for this article. [source] Factors driving pathogenicity vs. prevalence of amphibian panzootic chytridiomycosis in IberiaECOLOGY LETTERS, Issue 3 2010Susan F. Walker Ecology Letters (2010) 13: 372,382 Abstract Amphibian chytridiomycosis is a disease caused by the fungus Batrachochytrium dendrobatidis (Bd). Whether Bd is a new emerging pathogen (the novel pathogen hypothesis; NPH) or whether environmental changes are exacerbating the host-pathogen dynamic (the endemic pathogen hypothesis; EPH) is debated. To disentangle these hypotheses we map the distribution of Bd and chytridiomycosis across the Iberian Peninsula centred on the first European outbreak site. We find that the infection-free state is the norm across both sample sites and individuals. To analyse this dataset, we use Bayesian zero-inflated binomial models to test whether environmental variables can account for heterogeneity in both the presence and prevalence of Bd, and heterogeneity in the occurrence of the disease, chytridiomycosis. We also search for signatures of Bd -spread within Iberia using genotyping. We show (1) no evidence for any relationship between the presence of Bd and environmental variables, (2) a weak relationship between environmental variables and the conditional prevalence of infection, (3) stage-dependent heterogeneity in the infection risk, (4) a strong association between altitude and chytridiomycosis, (5) multiple Iberian genotypes and (6) recent introduction and spread of a single genotype of Bd in the Pyrenees. We conclude that the NPH is consistent with the emergence of Bd in Iberia. However, epizootic forcing of infection is tied to location and shaped by both biotic and abiotic variables. Therefore, the population-level consequences of disease introduction are explained by EPH-like processes. This study demonstrates the power of combining surveillance and molecular data to ascertain the drivers of new emerging infections diseases. [source] Alcohol Drinking Patterns and Health Care Utilization in a Managed Care OrganizationHEALTH SERVICES RESEARCH, Issue 3 2004Gary A. Zarkin Objective. To estimate the relationship between current drinking patterns and health care utilization over the previous two years in a managed care organization (MCO) among individuals who were screened for their alcohol use. Study Design. Three primary care clinics at a large western MCO administered a short health and lifestyle questionnaire to all adult patients on their first visit to the clinic from March 1998 through December 1998. Patients who exceeded the National Institute on Alcohol Abuse and Alcoholism (NIAAA) guidelines for moderate drinking were given a more comprehensive alcohol screening using a modified version of the Alcohol Use Disorders Identification Test (AUDIT). Health care encounter data for two years preceding the screening visit were linked to the remaining individuals who responded to one or both instruments. Using both quantity,frequency and AUDIT-based drinking pattern variables, we estimated negative binomial models of the relationship between drinking patterns and days of health care use, controlling for demographic characteristics and other variables. Principal Findings. For both the quantity,frequency and AUDIT-based drinking pattern variables, current alcohol use is generally associated with less health care utilization relative to abstainers. This relationship holds even for heavier drinkers, although the differences are not always statistically significant. With some exceptions, the overall trend is that more extensive drinking patterns are associated with lower health care use. Conclusions. Based on our sample, we find little evidence that alcohol use is associated with increased health care utilization. On the contrary, we find that alcohol use is generally associated with decreased health care utilization regardless of drinking pattern. [source] Nurse absenteeism and workload: negative effect on restraint use, incident reports and mortalityJOURNAL OF ADVANCED NURSING, Issue 6 2007Lynn Unruh Abstract Title.,Nurse absenteeism and workload: negative effect on restraint use, incident reports and mortality Aim., This paper is a report of a study to assess the impact of nurse absenteeism on the quality of patient care. Background., Nurse absenteeism is a growing management concern. It can contribute to understaffed units, staffing instability, and other factors that could have a negative impact on patient care. The impacts of absenteeism on the quality of nursing care have rarely been studied. Method., Retrospective monthly data from incident reports and staffing records in six inpatient units for 2004 were analysed. Dependent variables were the numbers of restraints, alternatives to restraints, incident reports, deaths, and length of stay. Explanatory variables were nurse absenteeism hours, patient days per nursing staff, and interaction between these variables. Controls were patient acuity and unit characteristics. Fixed effects regressions were analysed as regular or negative binomial models. Findings., Neither high Registered Nurse absenteeism nor high patient load was related to restraint use when taken separately. However, high Registered Nurse absenteeism was related to restraint use when patient load was high. Registered Nurse absenteeism was related to a lower use of alternatives to restraints. Incident reports were increased by high patient load, but not absenteeism, or absenteeism given patient load. When both patient load and absenteeism were high, deaths were higher also. Conclusion., Absenteeism alone may not be a strong factor in lowering quality, but the combination of high Registered Nurse absenteeism and high patient load could be a factor. Staffing and absenteeism may be part of a vicious cycle in which low staffing contributes to unit absenteeism, which contributes to low staffing, and so on. [source] Rural and Urban Disparities in Caries Prevalence in Children with Unmet Dental Needs: The New England Children's Amalgam TrialJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 1 2008Nancy Nairi Maserejian ScD Abstract Objectives: To compare the prevalence of caries between rural and urban children with unmet dental health needs who participated in the New England Children's Amalgam Trial. Methods: Baseline tooth and surface caries were clinically assessed in children from rural Maine (n = 243) and urban Boston (n = 291), who were aged 6 to 10 years, with two or more posterior carious teeth and no previous amalgam restorations. Statistical analyses used negative binomial models for primary dentition caries and zero-inflated models for permanent dentition caries. Results: Urban children had a higher mean number of carious primary surfaces (8.5 versus 7.4) and teeth (4.5 versus 3.9) than rural children. The difference remained statistically significant after adjusting for sociodemographic factors and toothbrushing frequency. In permanent dentition, urban children were approximately three times as likely to have any carious surfaces or teeth. However, rural/urban dwelling was not statistically significant in the linear analysis of caries prevalence among children with any permanent dentition caries. Covariates that were statistically significant in all models were age and number of teeth. Toothbrushing frequency was also important for permanent teeth. Conclusions: Within this population of New England children with unmet oral health needs, significant differences were apparent between rural and urban children in the extent of untreated dental decay. Results indicate that families who agree to participate in programs offering reduced cost or free dental care may present with varying amounts of dental need based on geographic location. [source] POISSON VERSUS BINOMIAL: APPOINTMENT OF JUDGES TO THE U.S. SUPREME COURTAUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 3 2010Vassilly Voinov Summary The problem of discriminating between the Poisson and binomial models is discussed in the context of a detailed statistical analysis of the number of appointments of the U.S. Supreme Court justices from 1789 to 2004. Various new and existing tests are examined. The analysis shows that both simple Poisson and simple binomial models are equally appropriate for describing the data. No firm statistical evidence in favour of an exponential Poisson regression model was found. Two attendant results were obtained by simulation: firstly, that the likelihood ratio test is the most powerful of those considered when testing for the Poisson versus binomial and, secondly, that the classical variance test with an upper-tail critical region is biased. [source] Prospective study of 5-year caries increment among children receiving comprehensive dental care in the New England children's amalgam trialCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 1 2009Nancy Nairi Maserejian Abstract,,, Objective:, To measure the 5-year caries increment among high-risk children during their participation in the New England Children's Amalgam Trial (NECAT), and to evaluate sociodemographic factors that may account for any observed disparities. Methods:, NECAT recruited 534 children aged 6,10 with at least two decayed posterior occlusal surfaces from urban Boston and rural Maine. After restoration of baseline caries and application of sealants to sound surfaces, NECAT continued to provide free comprehensive semiannual dental care to participants. The net caries increment of children who completed the 5-year follow-up (n = 429) was calculated and predictors of caries increment were investigated using multivariate negative binomial models. Results:, The majority of children (89%) experienced new caries by the end of the 5-year follow-up. Almost half (45%) had at least one newly decayed surface by the first annual visit. At year 5, the mean number of new decayed teeth was 4.5 ± 3.6 (range 0,25) and surfaces was 6.9 ± 6.5 (range 0,48). Time trends showed a noticeably higher increment rate among older children and young teenagers. Multivariate models showed that age (P < 0.001), number of baseline carious surfaces (P < 0.001), and toothbrushing frequency (<1/day versus ,2/day, P = 0.04) were associated with caries increment. Only 48 children (11%) did not develop new caries. Conclusions:, Despite the receipt of comprehensive semiannual dental care, the vast majority of these high-risk children continued to develop new caries within 5 years. While disparities were observed by age, extent of prior decay, and toothbrushing frequency, no other sociodemographic factors were associated with caries increment, suggesting that the dental care provided during the trial reduced sociodemographic disparities in prior caries experience that were observed at baseline. [source] | |||||||||||||