With digital equipment becoming increasingly networked, either on wired or wireless networks, for personal and professional use alike, distributed software systems have become a crucial element in information and communications technologies. The study of these systems forms the core of the ARLES' work, which is specifically concerned with defining new system software architectures, based on the use of emerging networking technologies. In this context, we concentrate on the study of distributed systems which bring to life the vision of ubiquitous computing systems, also known as ambient intelligence.

반도체 공정 overview

OBJECTIVES: To consider methods and related evidence for evaluating bias in non-randomised intervention studies. DATA SOURCES: Systematic reviews and methodological papers were identified from a search of electronic databases; handsearches of key medical journals and contact with experts working in the field. New empirical studies were conducted using data from two large randomised clinical trials. METHODS: Three systematic reviews and new empirical investigations were conducted. The reviews considered, in regard to non-randomised studies, (1) the existing evidence of bias, (2) the content of quality assessment tools, (3) the ways that study quality has been assessed and addressed. (4) The empirical investigations were conducted generating non-randomised studies from two large, multicentre randomised controlled trials (RCTs) and selectively resampling trial participants according to allocated treatment, centre and period. RESULTS: In the systematic reviews, eight studies compared results of randomised and non-randomised studies across multiple interventions using meta-epidemiological techniques. A total of 194 tools were identified that could be or had been used to assess non-randomised studies. Sixty tools covered at least five of six pre-specified internal validity domains. Fourteen tools covered three of four core items of particular importance for non-randomised studies. Six tools were thought suitable for use in systematic reviews. Of 511 systematic reviews that included non-randomised studies, only 169 (33%) assessed study quality. Sixty-nine reviews investigated the impact of quality on study results in a quantitative manner. The new empirical studies estimated the bias associated with non-random allocation and found that the bias could lead to consistent over- or underestimations of treatment effects, also the bias increased variation in results for both historical and concurrent controls, owing to haphazard differences in case-mix between groups. The biases were large enough to lead studies falsely to conclude significant findings of benefit or harm. Four strategies for case-mix adjustment were evaluated: none adequately adjusted for bias in historically and concurrently controlled studies. Logistic regression on average increased bias. Propensity score methods performed better, but were not satisfactory in most situations. Detailed investigation revealed that adequate adjustment can only be achieved in the unrealistic situation when selection depends on a single factor. CONCLUSIONS: Results of non-randomised studies sometimes, but not always, differ from results of randomised studies of the same intervention. Non-randomised studies may still give seriously misleading results when treated and control groups appear similar in key prognostic factors. Standard methods of case-mix adjustment do not guarantee removal of bias. Residual confounding may be high even when good prognostic data are available, and in some situations adjusted results may appear more biased than unadjusted results. Although many quality assessment tools exist and have been used for appraising non-randomised studies, most omit key quality domains. Healthcare policies based upon non-randomised studies or systematic reviews of non-randomised studies may need re-evaluation if the uncertainty in the true evidence base was not fully appreciated when policies were made. The inability of case-mix adjustment methods to compensate for selection bias and our inability to identify non-randomised studies that are free of selection bias indicate that non-randomised studies should only be undertaken when RCTs are infeasible or unethical. Recommendations for further research include: applying the resampling methodology in other clinical areas to ascertain whether the biases described are typical; developing or refining existing quality assessment tools for non-randomised studies; investigating how quality assessments of non-randomised studies can be incorporated into reviews and the implications of individual quality features for interpretation of a review's results; examination of the reasons for the apparent failure of case-mix adjustment methods; and further evaluation of the role of the propensity score.

/pdf/evaluating-non-randomised-intervention-studies-2k25cz7x6r.pdf

Evaluating non-randomised intervention studies.

Our future: a Lancet commission on adolescent health and wellbeing

ContextThe global refugee crisis requires that researchers, policymakers, and
clinicians comprehend the magnitude of the psychological consequences of forced
displacement and the factors that moderate them. To date, no empirical synthesis
of research on these issues has been undertaken.ObjectiveTo meta-analytically establish the extent of compromised mental health
among refugees (including internally displaced persons, asylum seekers, and
stateless persons) using a worldwide study sample. Potential moderators of
mental health outcomes were examined, including enduring contextual variables
(eg, postdisplacement accommodation and economic opportunity) and refugee
characteristics.Data SourcesPublished studies (1959-2002) were obtained using broad searches of
computerized databases (PsycINFO and PILOTS), manual searches of reference
lists, and interviews with prominent authors.Study SelectionStudies were selected if they investigated a refugee group and at least
1 nonrefugee comparison group and reported 1 or more quantitative group comparison
on measures of psychopathology. Fifty-six reports met inclusion criteria (4.4%
of identified reports), yielding 59 independent comparisons and including
67 294 participants (22 221 refugees and 45 073 nonrefugees).Data ExtractionData on study and report characteristics, study participant characteristics,
and statistical outcomes were extracted using a coding manual and subjected
to blind recoding, which indicated high reliability. Methodological quality
information was coded to assess potential sources of bias.Data SynthesisEffect size estimates for the refugee-nonrefugee comparisons were averaged
across psychopathology measures within studies and weighted by sample size.
The weighted mean effect size was 0.41 (SD, 0.02; range, −1.36 to 2.91
[SE, 0.01]), indicating that refugees had moderately poorer outcomes. Postdisplacement
conditions moderated mental health outcomes. Worse outcomes were observed
for refugees living in institutional accommodation, experiencing restricted
economic opportunity, displaced internally within their own country, repatriated
to a country they had previously fled, or whose initiating conflict was unresolved.
Refugees who were older, more educated, and female and who had higher predisplacement
socioeconomic status and rural residence also had worse outcomes. Methodological
differences between studies affected effect sizes.ConclusionsThe sociopolitical context of the refugee experience is associated with
refugee mental health. Humanitarian efforts that improve these conditions
are likely to have positive impacts.

Predisplacement and postdisplacement factors associated with mental health of refugees and internally displaced persons: a meta-analysis.

Gaining a better understanding of the factors that affect the likelihood of a vehicle crash has been an area of research focus for many decades. However, in the absence of detailed driving data that would help improve the identification of cause and effect relationships with individual vehicle crashes, most researchers have addressed this problem by framing it in terms of understanding the factors that affect the frequency of crashes - the number of crashes occurring in some geographical space (usually a roadway segment or intersection) over some specified time period. This paper provides a detailed review of the key issues associated with crash-frequency data as well as the strengths and weaknesses of the various methodological approaches that researchers have used to address these problems. While the steady march of methodological innovation (including recent applications of random parameter and finite mixture models) has substantially improved our understanding of the factors that affect crash-frequencies, it is the prospect of combining evolving methodologies with far more detailed vehicle crash data that holds the greatest promise for the future.

http://ceprofs.tamu.edu/dlord/Papers/Lord-Mannering_Review.pdf

The statistical analysis of crash-frequency data: A review and assessment of methodological alternatives

Contains summaries of the knowledge regarding the effects of 128 road safety measures This title covers various areas of road safety including: traffic control; vehicle inspection; driver training; publicity campaigns; police enforcement; and, general policy instruments It also covers topics such as post-accident care, and speed cameras

/pdf/the-handbook-of-road-safety-measures-qqxucplyid.pdf

The Handbook of Road Safety Measures

The relationship between speed and road safety is a highly controversial and emotionally charged subject This report investigates the effects of changes in speed on the number of road accidents or road accident victims It is found that the relationship between speed and accidents or accident victims can be represented by a set of power functions, as postulated in the so called "Power Model" of the relationship between speed and road safety

/pdf/speed-and-road-accidents-an-evaluation-of-the-power-model-26qasuqhh0.pdf

Speed and road accidents : an evaluation of the power model

The non-linearity of risk and the promotion of environmentally sustainable transport

A meta-analysis of studies of road accident reporting in official accident statistics made in 13 countries is described here. A rigorous comparison of reporting levels between countries is difficult because of differences in the definitions of reportable accidents, reporting levels, and data sources used to assess reporting levels. Based on 49 studies in 13 countries, it is concluded that reporting of injuries in official accident statistics is incomplete at all levels of injury severity. In rounded values, the mean reporting level in the countries included was found to be 95 percent for fatal injuries according to the 30-day rule, 70 percent for serious injuries (admitted to hospital), 25 percent for slight injuries (treated as outpatients), and 10 percent for very slight injuries (treated outside hospitals). Reporting levels vary substantially among countries, ranging from 21 to 88 percent for hospital-treated injuries. Reporting is highest for car occupants and lowest for cyclists. In particular, single-vehicle bicycle accidents are very rarely reported in official road accident statistics.

Rune Elvik

Papers

The Handbook of Road Safety Measures

Speed and road accidents : an evaluation of the power model

The non-linearity of risk and the promotion of environmentally sustainable transport

Incomplete Accident Reporting: Meta-Analysis of Studies Made in 13 Countries:

Risk of road accident associated with the use of drugs: a systematic review and meta-analysis of evidence from epidemiological studies.