Estimation of the parameters of a population from a multi-censored sample

The specific problems in this thesis were the estimation of parameters of univariate populations from samples where multiple-points of censorship occur. The case of a sample subjected to multiple points of censorship (on the right) may be described as follows: A sample of n items is tested; when the first one fails at time x1, a random sample of k1 is withdrawn from the n-1 items still in test; the remaining items are observed until the second item fails at time x2, when k2 items are withdrawn; and the process of withdrawing a prescribed number k i at the time xi when the i-th failure occurs continues until the r-th failure occurs at time xr, at which time the remainder of the items are withdrawn;The method of maximum likelihood is employed to estimate the parameters for the exponential, the normal, and the gamma distributions. These estimates are, in certain cases, difficult to obtain. They require iteration; therefore, certain practical limitations exist for their use. A new method of solving the likelihood equations for the normal distribution is introduced, and a Delta function is tabulated to facilitate the solution. An extension of the censorship procedure to another general type is considered for estimation by the method of maximum likelihood;The non-parametric estimate of the probability of surviving (quantiles) is obtained, and a general method of estimation based on the quantiles is presented, which will yield reasonable results when the method of maximum likelihood cannot be used, and which will be reasonably efficient in comparison to the maximum likelihood estimates when these are available for comparison. It is shown that the method of estimation from the quantiles yields the maximum-likelihood estimate for the exponential distribution for all rules of censorship and the uniform distribution for a random sample. The quantile method is asymptotically equivalent to the methods of maximum likelihood for the parameters of the normal distribution. The method yields a simple result (best linear unbiased estimate) for the uniform distribution with single or multi-censorship. This is an advantage over the maximum-likelihood method, which does not furnish a simple result;The above results are illustrated by a number of examples taken from industrial experiments. It is possible, through the techniques presented, to utilize small samples such as exist in industry, and also, although curtailment exists, to have assurance of a certain number of complete life times from which to make estimates even where no prior knowledge---other than the distributional form---exists on the life times of the items tested

Baseline and greenhouse-gas emissions in extensive livestock enterprises, with a case study of feeding lipid to beef cattle

For accurate calculation of reductions in greenhouse-gas (GHG) emissions, methodologies under the Australian Government's Carbon Farming Initiative (CFI) depend on a valid assessment of the baseline and project emissions. Life-cycle assessments (LCAs) clearly show that enteric methane emitted from the rumen of cattle and sheep is the major source of GHG emissions from livestock enterprises. Where a historic baseline for a CFI methodology for livestock is required, the use of simulated data for cow-calf enterprises at six sites in southern Australia demonstrated that a 5-year rolling emission average will provide an acceptable trade off in terms of accuracy and stability, but this is a much shorter time period than typically used for LCA. For many CFI livestock methodologies, comparative or pair-wise baselines are potentially more appropriate than historic baselines. A case study of lipid supplementation of beef cows over winter is presented. The case study of a control herd of 250 cows used a comparative baseline derived from simple data on livestock numbers and class of livestock to quantify the emission abatement. Compared with the control herd, lipid supplementation to cows over winter increased livestock productivity, total livestock production and enterprise GHG emissions from 990 t CO2-e to 1022 t CO2-e. Energy embodied in the supplement and extra diesel used in transporting the supplement diminished the enteric-methane abatement benefit of lipid supplementation. Reducing the cow herd to 238 cows maintained the level of livestock production of the control herd and reduced enterprise emissions to 938 t CO2-e, but was not cost effective under the assumptions of this case study

Analysis of Weekday, Weekend, and Holiday Accident Frequencies

Trends in recent years have indicated that a significant percentage of weekend traffic is recreational and that the proportion of weekend trips is increasing. The energy crisis in late 1973, and the associated reduction in speed limit on March 1, 1974, affected weekend travel. A previous study by the Division of Research revealed that significant reductions in the number and rates of highway accidents, fatalities, and injuries coincided with the period of time generally referred to as the energy crisis . Lower speeds were considered to be a primary factor in the reduction of accidents. An alteration in weekend and holiday trips was suspected of contributing to the reduction of accident rates; however, information was lacking from which to make this determination. A comparison of accidents during weekday, weekend, and holiday periods was made; most of the data were for rural sections of two-lane roads, four-lane roads, interstate routes, and toll roads. On rural roads, the largest number of accidents have occurred on Saturdays, Fridays, and Sundays. Tuesdays generally had the lowest number of accidents. Fatal accidents on two-lane roads occurred in similar random patterns of distribution during the week. The highest rates for two-lane roads were on Sundays and Saturdays, and the rates for expressways (interstates and toll roads) were the highest on Sundays. Fatality rates were distributed similarly to the rates of all accidents. The percentage of accidents on weekends decreased steadily from 35 in 1973 to 32 in 1976. likewise, the percentage of fatalities on weekends showed gradual decreases. Accident rates on weekends were substantially higher than on weekdays. Rates of fatal and an accidents were lower during holiday periods than during weekends not involving holidays. Holiday periods had fewer accidents per day than weekends but had more accidents per day than weekdays. Traffic volumes, however, were significantly greater during holidays than on either weekends or weekdays

Baseline and greenhouse-gas emissions in extensive livestock enterprises, with a case study of feeding lipid to beef cattle

For accurate calculation of reductions in greenhouse-gas (GHG) emissions, methodologies under the Australian Government's Carbon Farming Initiative (CFI) depend on a valid assessment of the baseline and project emissions. Life-cycle assessments (LCAs) clearly show that enteric methane emitted from the rumen of cattle and sheep is the major source of GHG emissions from livestock enterprises. Where a historic baseline for a CFI methodology for livestock is required, the use of simulated data for cow-calf enterprises at six sites in southern Australia demonstrated that a 5-year rolling emission average will provide an acceptable trade off in terms of accuracy and stability, but this is a much shorter time period than typically used for LCA. For many CFI livestock methodologies, comparative or pair-wise baselines are potentially more appropriate than historic baselines. A case study of lipid supplementation of beef cows over winter is presented. The case study of a control herd of 250 cows used a comparative baseline derived from simple data on livestock numbers and class of livestock to quantify the emission abatement. Compared with the control herd, lipid supplementation to cows over winter increased livestock productivity, total livestock production and enterprise GHG emissions from 990 t CO2-e to 1022 t CO2-e. Energy embodied in the supplement and extra diesel used in transporting the supplement diminished the enteric-methane abatement benefit of lipid supplementation. Reducing the cow herd to 238 cows maintained the level of livestock production of the control herd and reduced enterprise emissions to 938 t CO2-e, but was not cost effective under the assumptions of this case study

Analysis of Weekday, Weekend, and Holiday Accident Frequencies

On rural roads, the largest number of accidents have occurred on Saturdays, Fridays, and Sundays, respectively. Tuesdays generally had the lowest number of accidents. The highest accident rates for two-lane roads were on Sundays and Saturdays, and the rates for expressways (interstates and toll roads) were the highest on Sundays. Accident rates on weekends were substantially higher than on weekdays. Rates of fatal and all accidents were lower during holiday periods than during weekends not involving holidays. Holiday periods had fewer accidents per day than weekends but had more accidents per day than weekdays. Traffic during holidays, however, was significantly greater than on either weekends or weekdays

The relevance of ERTS-1 data to the state of Ohio

There are no author-identified significant results in this report

Co-creating solutions to local mobility and transport challenges for the enhancement of health and wellbeing in an area of socioeconomic disadvantage

Introduction: The paper describes and examines a novel methodology to co-define transport and mobility challenges and co-create solutions with residents of a socioeconomically disadvantaged area within Oxford in the UK. The co-creation methodology is examined in relation to the extent of participation, inclusivity, transparency, interactivity, scale, sustainability/continuity, replicability, potential for co-benefits. Methods: A Citizen Mobility Community was established with local residents at the core, and including representatives from the local authority, and other stakeholders. The paper describes the main elements of the co-creation process applied to identify mobility challenges, identify solutions, endorse the mobility solutions, and develop the solutions into practical action. Setting: The setting was the Eastern Arc of Oxford, the most socioeconomically deprived area in Oxford. Results: A sequence of co-creation activities helped identify and understand the transport challenges in Barton in the Eastern Arc of Oxford. Challenges included the high cost of public transport, traffic congestion, particularly during morning peak times, and the lack of cross-connectivity and direct public transport routes to desirable locations including affordable supermarkets, train stations, workplaces, health services such as hospitals and other neighbourhoods. The co-creation methodology led to the development of three pilot interventions to address these challenges, namely face-to-face transport app training, a transport to supermarkets shuttle service, and an information campaign about concessionary bus passes. Analysis of the co-creation methodology found that the process achieved its aims of empowering citizens in decision making about addressing locally experienced transport challenges, and building social capital. Conclusions: The co-creation enables communities in areas of socioeconomic disadvantage to identify their transport challenges, and to co-develop and co-design practical solutions. Co-creation to address local transport needs builds community empowerment, creates social capital and may contribute, through plausible causal pathways, to improved health and wellbeing in an area of socioeconomic disadvantage

Effectiveness of testing, contact tracing and isolation interventions among the general population on reducing transmission of SARS-CoV-2: a systematic review

We conducted a systematic literature review of general population testing, contact tracing, case isolation and contact quarantine interventions to assess their effectiveness in reducing SARS-CoV-2 transmission, as implemented in real-world settings. We designed a broad search strategy and aimed to identify peer-reviewed studies of any design provided there was a quantitative measure of effectiveness on a transmission outcome. Studies that assessed the effect of testing or diagnosis on disease outcomes via treatment, but did not assess a transmission outcome, were not included. We focused on interventions implemented among the general population rather than in specific settings; these were from anywhere in the world and published any time after 1 January 2020 until the end of 2022. From 26 720 titles and abstracts, 1181 were reviewed as full text, and 25 met our inclusion criteria. These 25 studies included one randomized control trial (RCT) and the remaining 24 analysed empirical data and made some attempt to control for confounding. Studies included were categorized by the type of intervention: contact tracing (seven studies); specific testing strategies (12 studies); strategies for isolating cases/contacts (four studies); and 'test, trace, isolate' (TTI) as a part of a package of interventions (two studies). None of the 25 studies were rated at low risk of bias and many were rated as serious risk of bias, particularly due to the likely presence of uncontrolled confounding factors, which was a major challenge in assessing the independent effects of TTI in observational studies. These confounding factors are to be expected from observational studies during an on-going pandemic, when the emphasis was on reducing the epidemic burden rather than trial design. Findings from these 25 studies suggested an important public health role for testing followed by isolation, especially where mass and serial testing was used to reduce transmission. Some of the most compelling analyses came from examining fine-grained within-country data on contact tracing; while broader studies which compared behaviour between countries also often found TTI led to reduced transmission and mortality, this was not universal. There was limited evidence for the benefit of isolation of cases/contacts away from the home environment. One study, an RCT, showed that daily testing of contacts could be a viable strategy to replace lengthy quarantine of contacts. Based on the scarcity of robust empirical evidence, we were not able to draw any firm quantitative conclusions about the quantitative impact of TTI interventions in different epidemic contexts. While the majority of studies found that testing, tracing and isolation reduced transmission, evidence for the scale of this impact is only available for specific scenarios and hence is not necessarily generalizable. Our review therefore emphasizes the need to conduct robust experimental studies that help inform the likely quantitative impact of different TTI interventions on transmission and their optimal design. Work is needed to support such studies in the context of future emerging epidemics, along with assessments of the cost-effectiveness of TTI interventions, which was beyond the scope of this review but will be critical to decision-making. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'

Understanding the causes of local disputes in paediatrics to develop pathways to dispute resolution in North East Scotland. [RCPCH Poster]

Conflicts over the care of children with life-limiting conditions can reach the point where courts have to intervene,but giving evidence causes distress, unwanted media attention and costs. The decision in Charlie Gard’s case in Englandincluded a plea for parties to mediate. No case has arisen in Scotland, where law and practice differ, but there are approximately 16,000 children with complex conditions where care might potentially be disputed. This study seeks to understand reasons for disputes, identify potential solutions (including mediation) and reduce the risk of a case coming before a Scottish court. In-depth interviews (online and face-to-face) with NHS Grampian clinicians and parents were conducted from which qualitative data were obtained on their experiences and views on disagreements about care, how decision-making is handled, what works well and what might improve existing approaches. This is being funded by the NHS Grampian Endowment Fund. Ten clinicians and five parents were interviewed. Preliminary thematic analysis suggests that clinicians feel multidisciplinary team meetings improve conflict resolution for patients with complex requirements, where specialism boundaries can blur. When disputes arise, the type of intervention varied depending on its scale, urgency and impact on other care teams. A cause of disputes is variation in goals within and between care teams, but micro-discussions and step-bystep approaches from the outset work well and mitigate risk of disputes. The settings, timing and language used in conversations with parents is important. Findings suggest that clinicians may prefer a two-stage process where meetings are held without parents in the first instance. A strong Chair facilitates useful meetings, but parents still find it difficult to know who to address questions to. Families' use of social media/online searches can be problematic and lead to strained relationships, but emphasis on 'good death' and 'doing what's right' were highlighted. When a child is hospitalised, 'handing over' a child who has been looked after at home can be difficult for parents and home care teams. A desire to connect with parents facing similar challenges was expressed. It is clear that conflict exists in Scottish paediatric care. Practice suggests that there are strategies which can be employed to minimise risk of intractable disputes arising which could be used to assess the suitability of mediation and formalised into a toolkit to support families and clinicians