1,487 research outputs found
The Bayesian Decision Tree Technique with a Sweeping Strategy
The uncertainty of classification outcomes is of crucial importance for many
safety critical applications including, for example, medical diagnostics. In
such applications the uncertainty of classification can be reliably estimated
within a Bayesian model averaging technique that allows the use of prior
information. Decision Tree (DT) classification models used within such a
technique gives experts additional information by making this classification
scheme observable. The use of the Markov Chain Monte Carlo (MCMC) methodology
of stochastic sampling makes the Bayesian DT technique feasible to perform.
However, in practice, the MCMC technique may become stuck in a particular DT
which is far away from a region with a maximal posterior. Sampling such DTs
causes bias in the posterior estimates, and as a result the evaluation of
classification uncertainty may be incorrect. In a particular case, the negative
effect of such sampling may be reduced by giving additional prior information
on the shape of DTs. In this paper we describe a new approach based on sweeping
the DTs without additional priors on the favorite shape of DTs. The
performances of Bayesian DT techniques with the standard and sweeping
strategies are compared on a synthetic data as well as on real datasets.
Quantitatively evaluating the uncertainty in terms of entropy of class
posterior probabilities, we found that the sweeping strategy is superior to the
standard strategy
Integrating the promotion of physical activity within a smoking cessation programme: Findings from collaborative action research in UK Stop Smoking Services
Background: Within the framework of collaborative action research, the aim was to explore the feasibility of
developing and embedding physical activity promotion as a smoking cessation aid within UK 6/7-week National
Health Service (NHS) Stop Smoking Services.
Methods: In Phase 1 three initial cycles of collaborative action research (observation, reflection, planning,
implementation and re-evaluation), in an urban Stop Smoking Service, led to the development of an integrated
intervention in which physical activity was promoted as a cessation aid, with the support of a theoretically based
self-help guide, and self monitoring using pedometers. In Phase 2 advisors underwent training and offered the
intervention, and changes in physical activity promoting behaviour and beliefs were monitored. Also, changes in
clients’ stage of readiness to use physical activity as a cessation aid, physical activity beliefs and behaviour and
physical activity levels were assessed, among those who attended the clinic at 4-week post-quit. Qualitative data
were collected, in the form of clinic observation, informal interviews with advisors and field notes.
Results: The integrated intervention emerged through cycles of collaboration as something quite different to
previous practice. Based on field notes, there were many positive elements associated with the integrated
intervention in Phase 2. Self-reported advisors’ physical activity promoting behaviour increased as a result of
training and adapting to the intervention. There was a significant advancement in clients’ stage of readiness to use physical activity as a smoking cessation aid.
Conclusions: Collaboration with advisors was key in ensuring that a feasible intervention was developed as an aid to smoking cessation. There is scope to further develop tailored support to increasing physical activity and
smoking cessation, mediated through changes in perceptions about the benefits of, and confidence to do physical activity
How clumpy is my image? Evaluating crowdsourced annotation tasks
13th UK Workshop on Computational Intelligence (UKCI), Guildford, UK, 9-11 September 2013This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The use of citizen science to obtain annotations from multiple annotators has been shown to be an effective method for annotating datasets in which computational methods alone are not feasible. The way in which the annotations are obtained is an important consideration which affects the quality of the resulting consensus estimates. In this paper, we examine three separate approaches to obtaining scores for instances rather than merely classifications. To obtain a consensus score annotators were asked to make annotations in one of three paradigms: classification, scoring and ranking. A web-based citizen science experiment is described which implements the three approaches as crowdsourced annotation tasks. The tasks are evaluated in relation to the accuracy and agreement among the participants using both simulated and real-world data from the experiment. The results show a clear difference in performance between the three tasks, with the ranking task obtaining the highest accuracy and agreement among the participants. We show how a simple evolutionary optimiser may be used to improve the performance by reweighting the importance of annotators
SRB Environment Evaluation and Analysis. Volume 3: ASRB Plume Induced Environments
Contract NAS8-37891 was expanded in late 1989 to initiate analysis of Shuttle plume induced environments as a result of the substitution of the Advanced Solid Rocket Booster (ASRB) for the Redesigned Solid Rocket Booster (RSRB). To support this analysis, REMTECH became involved in subscale and full-scale solid rocket motor test programs which further expanded the scope of work. Later contract modifications included additional tasks to produce initial design cycle environments and to specify development flight instrumentation. Volume 3 of the final report describes these analyses and contains a summary of reports resulting from various studies
Optimising decision trees using multi-objective particle swarm optimisation
Copyright © 2009 Springer-Verlag Berlin Heidelberg. The final publication is available at link.springer.comBook title: Swarm Intelligence for Multi-objective Problems in Data MiningSummary.
Although conceptually quite simple, decision trees are still among the most popular classifiers applied to real-world problems. Their popularity is due to a number of factors – core among these is their ease of comprehension, robust performance and fast data processing capabilities. Additionally feature selection is implicit within the decision tree structure.
This chapter introduces the basic ideas behind decision trees, focusing on decision trees which only consider a rule relating to a single feature at a node (therefore making recursive axis-parallel slices in feature space to form their classification boundaries). The use of particle swarm optimization (PSO) to train near optimal decision trees is discussed, and PSO is applied both in a single objective formulation (minimizing misclassification cost), and multi-objective formulation (trading off misclassification rates across classes).
Empirical results are presented on popular classification data sets from the well-known UCI machine learning repository, and PSO is demonstrated as being fully capable of acting as an optimizer for trees on these problems. Results additionally support the argument that multi-objectification of a problem can improve uni-objective search in classification problems
Pigmentary keratitis in pugs in the United Kingdom: prevalence and associated features
BACKGROUND: Pigmentary keratitis (PK) is commonly recognised in Pugs, but its aetiology is not completely understood. The aim of this study was to determine the prevalence and associated features of PK in Pugs in the United Kingdom (UK). RESULTS: A total of 210 Pugs (420 eyes) were recruited from 12 UK dog shows and social events. The median age of Pugs recruited was 2.50 years (range 0.25-16.25 years). Pigmentary keratitis was detected in 369/420 (87.8%) eyes and in at least one eye 193/210 (91.9%) Pugs, of which 17/193 (8.8%) were affected unilaterally and 176/193 (91.2%) bilaterally. Pigmentary keratitis was typically mild to moderate (46.3 and 49.9% of eyes, respectively). Detection of PK was significantly associated with increased age (P = 0.002) and the presence of medial entropion of the lower eyelid (MELE) (P = 0.001). Severity of PK was significantly associated with the grade of MELE (P < 0.001). There was also a correlation between the presence of limbal pigment and PK (P = 0.036) that warrants further study. CONCLUSIONS: This study estimated a high disease prevalence of PK in UK Pugs, and demonstrated significant associations with age and the presence of MELE. These associations, which have not been previously reported, offer an insight into the underlying pathophysiology of this condition in Pugs. The results encourage further population research, such as prospective longitudinal studies. These findings also support the development of clinical and breeding strategies based on the reduction of MELE and, possibly, limbal pigment.</p
Effect of Human Exogenous Leukocyte Interferon in Cytomegalovirus Infections
Human leukocyte interferon was injected into nine patients with cytomegalovirus infections; four of these patients were congenitally infected, and five had acquired infections. In three patients viruria was completely inhibited. In five patients viral excretion in the urine was only transiently inhibited. Viremia was not significantly suppressed. The lymphocyte response to phytohemagglutinin was suppressed in two patient
Riddled-like Basin in Two-Dimensional Map for Bouncing Motion of an Inelastic Particle on a Vibrating Board
Motivated by bouncing motion of an inelastic particle on a vibrating board, a
simple two-dimensional map is constructed and its behavior is studied
numerically. In addition to the typical route to chaos through a periodic
doubling bifurcation, we found peculiar behavior in the parameter region where
two stable periodic attractors coexist. A typical orbit in the region goes
through chaotic motion for an extended transient period before it converges
into one of the two periodic attractors. The basin structure in this parameter
region is almost riddling and the fractal dimension of the basin boundary is
close to two, {\it i.e.}, the dimension of the phase space.Comment: 4 pages, 5 figures. to be published in J. Phys. Soc. Jpn. (2002
Can clinical audits be enhanced by pathway simulation and machine learning? An example from the acute stroke pathway
OBJECTIVE:
To evaluate the application of clinical pathway simulation in machine learning, using clinical audit data, in order to identify key drivers for improving use and speed of thrombolysis at individual hospitals
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