89 research outputs found

    Detecting patterns in Time Series Data with applications in Official Statistics

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    This thesis examines the issue of detecting components or features within time series data in automatic procedures. We begin by introducing the concept of Wavelets and briefly show their usage as a tool for detection. This leads to our first contribution which is a novel method using wavelets for identifying correlation structures in time series data which are often ambiguous with very different contexts. Using the properties of the wavelet transform we show the ability to distinguish between short memory models with changepoints and long memory models. The next two Chapters consider seasonality within data, which is often present in time series used in Offical Statistics. We first describe the historical evolution of identification of seasonality, comparing and contrasting methodology as it has expanded throughout time. Following this, motivated by the increased use of high-frequency time series in Official Statistics and a lack of methods for identifying low-frequency seasonal components within high-frequency data, we present a method for identifying periodicity in a series with the use of a simple wavelet decomposition. Presented with theoretical results and simulations, we show how the seasonality of a series is uniquely represented within a wavelet transform and use this to identify low frequency components which are often overlooked in favour of a trend, with very different interpretations. Finally, beginning with the motivation of forecasting European Area GDP at the current time point, we show the effectiveness of an algorithm which detects the most useful data and structures for a Dynamic Factor Model. We show its effectiveness in reducing forecasting errors but show that under large scale simulation that the recovery of the true structure over two dimensions is a difficult task. All the chapters of this thesis are motivated by, and give applications to, time series from different areas of Official Statistics

    Long memory and changepoint models:a spectral classification procedure

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    Time series within fields such as finance and economics are often modelled using long memory processes. Alternative studies on the same data can suggest that series may actually contain a ‘changepoint’ (a point within the time series where the data generating process has changed). These models have been shown to have elements of similarity, such as within their spectrum. Without prior knowledge this leads to an ambiguity between these two models, meaning it is difficult to assess which model is most appropriate. We demonstrate that considering this problem in a time-varying environment using the time-varying spectrum removes this ambiguity. Using the wavelet spectrum, we then use a classification approach to determine the most appropriate model (long memory or changepoint). Simulation results are presented across a number of models followed by an application to stock cross-correlations and US inflation. The results indicate that the proposed classification outperforms an existing hypothesis testing approach on a number of models and performs comparatively across others

    Patients' attitudes towards cost feedback to doctors to prevent unnecessary testing: a qualitative focus group study

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    © 2020 The Authors Objectives: There is a need to improve efficiency in healthcare delivery without compromising quality of care. One approach is the development and evaluation of behavioural strategies to reduce unnecessary use of common tests. However, there is an absence of evidence on patient attitudes to the use of such approaches in the delivery of care. Our objective was to explore patient acceptability of a nudge-type intervention that aimed to modify blood test requests by hospital doctors. Study design: Single-centre qualitative study. Methods: The financial costs of common blood tests were presented to hospital doctors on results reports for 1 year at a hospital. Focus group discussions were conducted with recent inpatients at the hospital using a semi-structured question schedule. Discussions were transcribed and analysed using qualitative content analysis to identify and prioritise common themes explaining attitudes to the intervention approach. Results: Three focus groups involving 17 participants were conducted. Patients were generally apprehensive about the provision of blood test cost feedback to doctors. Attitudes were organised around themes representing beliefs about blood tests, the impact on doctors and their autonomy, and beliefs about unnecessary testing. Patients thought that blood tests were important, powerful and inexpensive, and cost information could place doctors under additional pressure. Conclusion: The findings identify predominantly positive beliefs about testing and negative attitudes to the use of financial costs in the decision-making of hospital doctors. Public discussion and education about the possible overuse of common tests may allow more resources to be allocated to evidence-based healthcare, by reducing the perception that such strategies to improve healthcare efficiency negatively impact on quality of care

    Hospital doctors’ attitudes to brief educational messages that aim to modify diagnostic test requests: a qualitative study

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    Background: Avoidable use of diagnostic tests can both harm patients and increase the cost of healthcare. Nudge-type educational interventions have potential to modify clinician behaviour while respecting clinical autonomy and responsibility, but there is little evidence how this approach may be best used in a healthcare setting. This study aims to explore attitudes of hospital doctors to two nudge-type messages: one concerning potential future cancer risk after receiving a CT scan, another about the financial costs of blood tests. Methods: We added two brief educational messages to diagnostic test results in a UK hospital for one year. One message on the associated long-term potential cancer risk from ionising radiation imaging to CT scan reports, and a second on the financial costs incurred to common blood test results. We conducted a qualitative study involving telephone interviews with doctors working at the hospital to identify themes explaining their response to the intervention. Results: Twenty eight doctors were interviewed. Themes showed doctors found the intervention to be highly acceptable, as the group had a high awareness of the need to prevent harm and optimise use of finite resources, and most found the nudge-type approach to be inoffensive and harmless. However, the messages were not seen as personally relevant because doctors felt they were already relatively conservative in their use of tests. Cancer risk was important in decision-making but was not considered to represent new knowledge to doctors. Conversely, financial costs were considered to be novel information that was unimportant in decision-making. Defensive medicine was commonly cited as a barrier to individual behaviour change. The educational cancer risk message on CT scan reports increased doctors’ confidence to challenge decisions and explain risks to patients and there were some modifications in clinical practice prompted by the financial cost message. Conclusion: The nudge-type approach to target avoidable use of tests was acceptable to hospital doctors but there were barriers to behaviour change. There was evidence doctors perceived this cheap and light-touch method can contribute to culture change and form a foundation for more comprehensive educational efforts to modify behaviour in a healthcare environment

    Estimated Environmental Exposures for MISSE-7B

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    This paper details the 18-month environmental exposure for Materials International Space Station Experiment 7B (MISSE-7B) ram and wake sides. This includes atomic oxygen, ultraviolet radiation, particulate radiation, thermal cycling, meteoroid/space debris impacts, and observed contamination. Atomic oxygen fluence was determined by measured mass and thickness loss of polymers of known reactivity. Diodes sensitive to ultraviolet light actively measured solar radiation incident on the experiment. Comparisons to earlier MISSE flights are discussed

    Evaluation of the impact of a brief educational message on clinicians’ awareness of risks of ionising-radiation exposure in imaging investigations:a pilot pre-post intervention study

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    Background:In the context of increasing availability of computed tomography (CT) scans, judicious use of ionising radiation is a priority to minimise the risk of future health problems. Hence, education of clinicians on the risks and benefits of CT scans in the management of patients is important. Methods:An educational message about the associated lifetime cancer risk of a CT scan was added to all CT scan reports at a busy acute teaching hospital in the UK. An online multiple choice survey was completed by doctors before and after the intervention, assessing education and knowledge of the risks involved with exposure to ionising radiation.Results:Of 546 doctors contacted at baseline, 170 (31%) responded. Over a third (35%) of respondents had received no formal education on the risks of exposure to ionising radiation. Over a quarter (27%) underestimated (selected 1 in 30 000 or negligible lifetime cancer risk) the risk associated with a chest, abdomen and pelvis CT scan for a 20 year old female. Following exposure to the intervention for one year there was a statistically significant improvement in plausibleestimates of risk from 68.3% to 82.2% of respondents (p < 0.001). There was no change in the proportion of doctors correctly identifying imaging modalities that do or do not involve ionising radiation.Conclusions:Training on the longterm risks associated with diagnostic radiation exposure is inadequate among hospital doctors.Exposure to a simple non-directional educational message for one year improved doctors’ awareness of risks associated with CT scans. This demonstrates the potential of the approach to improve knowledge that could improve clinical practice. This approach is easily deliverable and may have applications in other areas of clinical medicine. The wider and longer term impact on radiation awareness is unknown, however, and there may be a need for regular mandatory training in the risks of radiation exposure

    Evaluation of a nudge intervention providing simple feedback to clinicians of the consequence of radiation exposure on demand for computed tomography: a controlled study

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    Computerised tomography (CT) is readily available in developed countries. As one of the side-effects includes an increased risk of cancer, interventions that may encourage more judicious use of CT scans are important. Behavioural economics theory includes the use of nudges that aim to help more informed decisions to be made, although these have been rarely used in hospitals to date. We aimed to evaluate the impact of a simple educational message appended to the CT scan report on subsequent numbers of CT scans completed using a controlled interrupted time series design based in two teaching hospitals in X. The intervention was the addition of a non-directional educational message on the risk of ionising radiation to all CT scan reports. There was a statistically significant reduction in the number of CT scans requested in the intervention hospital compared to the control hospital (-4.6%, 95% confidence intervals -7.4 to -1.7, p = 0.002) in the 12 months after the intervention was implemented. We conclude that a simple, non-directional nudge intervention has the capacity to modify clinician use of CT scans. This approach is cheap, and has potential in helping support doctors make informed decisions

    Does cost feedback modify demand for common blood tests in secondary care? A prospective controlled intervention study

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    Background: Behavioural insights or ‘nudge’ theory suggests that non-directional interventions may be used to modify human behaviour. We have tested the hypothesis that the provision of the cost of common blood tests with their results may modify subsequent demand for blood assays.Methods: The study design was a prospective controlled intervention study. The individual and annual institutional cost of full blood count (FBC), urea and electrolytes (U&E) and liver function test (LFT) blood assays were added to the electronic results system for inpatients at the intervention teaching hospital, but not the control hospital.Results: In the 12 months after the intervention was implemented, demand for FBC dropped by 3% (95% confidence intervals [CI]: 1 to 5, p less than 0.001), U&E by 2% (95%CI: 0 to 4, p=0.054) and there was no change in demand for LFT compared to the control institution.Conclusions: Providing cost feedback to clinicians for commonly used blood tests is a viable intervention that is associated with small reductions in demand for some, but not all blood assays. As this is an easily scalable approach, this has potential to enable efficient health care delivery, while also minimising the morbidity experienced by the patient

    Design and baseline characteristics of the finerenone in reducing cardiovascular mortality and morbidity in diabetic kidney disease trial

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    Background: Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. Patients and Methods: The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate >= 25 mL/min/1.73 m(2) and albuminuria (urinary albumin-to-creatinine ratio >= 30 to <= 5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level alpha = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. Conclusions: FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049