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Accident prediction models with random corridor parameters.

https://arctichealth.org/en/permalink/ahliterature149229
Source
Accid Anal Prev. 2009 Sep;41(5):1118-23
Publication Type
Article
Date
Sep-2009
Author
Karim El-Basyouny
Tarek Sayed
Author Affiliation
Dept. of Civil Engineering, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. basyouny@civil.ubc.ca
Source
Accid Anal Prev. 2009 Sep;41(5):1118-23
Date
Sep-2009
Language
English
Publication Type
Article
Keywords
Accidents, Traffic - statistics & numerical data
Analysis of Variance
Bayes Theorem
British Columbia
Humans
Markov Chains
Models, Statistical
Models, Theoretical
Poisson Distribution
Risk assessment
Statistics as Topic
Abstract
Recent research advocates the use of count models with random parameters as an alternative method for analyzing accident frequencies. In this paper a dataset composed of urban arterials in Vancouver, British Columbia, is considered where the 392 segments were clustered into 58 corridors. The main objective is to assess the corridor effects with alternate specifications. The proposed models were estimated in a Full Bayes context via Markov Chain Monte Carlo (MCMC) simulation and were compared in terms of their goodness of fit and inference. A variety of covariates were found to significantly influence accident frequencies. However, these covariates resulted in random parameters and thereby their effects on accident frequency were found to vary significantly across corridors. Further, a Poisson-lognormal (PLN) model with random parameters for each corridor provided the best fit. Apart from the improvement in goodness of fit, such an approach is useful in gaining new insights into how accident frequencies are influenced by the covariates, and in accounting for heterogeneity due to unobserved road geometrics, traffic characteristics, environmental factors and driver behavior. The inclusion of corridor effects in the mean function could also explain enough variation that some of the model covariates would be rendered non-significant and thereby affecting model inference.
PubMed ID
19664455 View in PubMed
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Acute middle ear infection in small children: a Bayesian analysis using multiple time scales.

https://arctichealth.org/en/permalink/ahliterature33815
Source
Lifetime Data Anal. 1998;4(2):121-37
Publication Type
Article
Date
1998
Author
A. Andreev
E. Arjas
Author Affiliation
Department of Mathematical Sciences, University of Oulu, Finland.
Source
Lifetime Data Anal. 1998;4(2):121-37
Date
1998
Language
English
Publication Type
Article
Keywords
Acute Disease
Algorithms
Bayes Theorem
Child, Preschool
Cohort Studies
Female
Finland - epidemiology
Humans
Incidence
Infant
Infant, Newborn
Likelihood Functions
Male
Markov Chains
Mathematical Computing
Models, Statistical
Otitis Media - epidemiology
Prospective Studies
Research Support, Non-U.S. Gov't
Risk factors
Abstract
The study is based on a sample of 965 children living in Oulu region (Finland), who were monitored for acute middle ear infections from birth to the age of two years. We introduce a nonparametrically defined intensity model for ear infections, which involves both fixed and time dependent covariates, such as calendar time, current age, length of breast-feeding time until present, or current type of day care. Unmeasured heterogeneity, which manifests itself in frequent infections in some children and rare in others and which cannot be explained in terms of the known covariates, is modelled by using individual frailty parameters. A Bayesian approach is proposed to solve the inferential problem. The numerical work is carried out by Monte Carlo integration (Metropolis-Hastings algorithm).
PubMed ID
9658771 View in PubMed
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Aflibercept vs. Ranibizumab: cost-effectiveness of treatment for wet age-related macular degeneration in Sweden.

https://arctichealth.org/en/permalink/ahliterature279115
Source
Acta Ophthalmol. 2016 Aug;94(5):441-8
Publication Type
Article
Date
Aug-2016
Author
Hemangi R Panchmatia
Karen M Clements
Erin Hulbert
Marianne Eriksson
Kim Wittrup-Jensen
Jonas Nilsson
Milton C Weinstein
Source
Acta Ophthalmol. 2016 Aug;94(5):441-8
Date
Aug-2016
Language
English
Publication Type
Article
Keywords
Aged
Aged, 80 and over
Angiogenesis Inhibitors - administration & dosage - economics
Cost-Benefit Analysis
Female
Health Care Costs
Humans
Intravitreal Injections
Male
Markov Chains
Middle Aged
Models, Statistical
Quality-Adjusted Life Years
Randomized Controlled Trials as Topic
Ranibizumab - administration & dosage - economics
Receptors, Vascular Endothelial Growth Factor - administration & dosage
Recombinant Fusion Proteins - administration & dosage - economics
Sweden
Vascular Endothelial Growth Factor A - antagonists & inhibitors
Visual Acuity - drug effects
Wet Macular Degeneration - drug therapy - economics
Abstract
Monthly dosing with ranibizumab (RBZ) is needed to achieve maximal visual gains in patients with neovascular ('wet') age-related macular degeneration (wAMD). In Sweden, dosing is performed as needed (RBZ PRN), resulting in suboptimal efficacy. Intravitreal aflibercept (IVT-AFL) every 2 months after three initial monthly doses was clinically equivalent to RBZ monthly dosing (RBZ q4) in wAMD clinical trials. We assessed the cost-effectiveness of IVT-AFL versus RBZ q4 and RBZ PRN in Sweden.
A Markov model compared IVT-AFL to RBZ q4 or RBZ PRN over 2 years. Health states were based on visual acuity in better-seeing eye; a proportion discontinued treatment monthly or upon visual acuity
PubMed ID
27061020 View in PubMed
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Ages of mutations on a coalescent tree.

https://arctichealth.org/en/permalink/ahliterature203995
Source
Math Biosci. 1998 Oct;153(1):41-61
Publication Type
Article
Date
Oct-1998
Author
R. Thomson
Author Affiliation
Mathematics Department, Monash University, Clayton, Vic., Australia. rjt@mws4.biol.berkeley.edu
Source
Math Biosci. 1998 Oct;153(1):41-61
Date
Oct-1998
Language
English
Publication Type
Article
Keywords
Base Sequence - genetics
British Columbia
DNA, Mitochondrial - genetics
Female
Genetics, Population
Humans
Indians, North American - genetics
Male
Markov Chains
Models, Biological
Mutation - genetics
Numerical Analysis, Computer-Assisted
Phylogeny
Poisson Distribution
Population Dynamics
Washington
Abstract
Using the coalescent process, DNA sequences of a sample of individuals can be used to study the phylogenetic history of the individuals. Under the infinitely-many-sites mutation model, the DNA sequence data can be summarized by the number of segregating sites (which is numerically equivalent to the number of mutations on the tree). A number of methods exist, including a recursive method presented in this paper, that obtain an estimate of the age of the most recent common ancestor (MRCA), given the number of mutations. This paper introduces a method for finding the ages of mutations, given the total number of mutations on the tree. While the result is not useful in estimating the age of a specific segregating site, it is useful in examining the underlying assumption of a relatively constant population over time. This utilization of the result is illustrated using DNA sequence data obtained from a sample of Amerindians of the Nuu-Chah-Nulth tribe.
PubMed ID
9810160 View in PubMed
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Aging of the population may not lead to an increase in the numbers of acute coronary events: a community surveillance study and modelled forecast of the future.

https://arctichealth.org/en/permalink/ahliterature114624
Source
Heart. 2013 Jul;99(13):954-9
Publication Type
Article
Date
Jul-2013
Author
Veikko Salomaa
Aki S Havulinna
Heli Koukkunen
Päivi Kärjä-Koskenkari
Arto Pietilä
Juha Mustonen
Matti Ketonen
Aapo Lehtonen
Pirjo Immonen-Räihä
Seppo Lehto
Juhani Airaksinen
Y Antero Kesäniemi
Author Affiliation
Department of Chronic Disease Prevention, THL-National Institute for Health and Welfare, PO Box 30, Helsinki FI-00271, Finland. veikko.salomaa@thl.fi
Source
Heart. 2013 Jul;99(13):954-9
Date
Jul-2013
Language
English
Publication Type
Article
Keywords
Acute Coronary Syndrome - epidemiology - mortality
Age Factors
Age of Onset
Aged
Aging
Bayes Theorem
Comorbidity
Computer simulation
Epidemiology - trends
Female
Finland - epidemiology
Forecasting
Humans
Incidence
Logistic Models
Male
Markov Chains
Middle Aged
Models, Statistical
Monte Carlo Method
Registries
Survivors - statistics & numerical data
Time Factors
Abstract
To examine the incidence, mortality and case fatality of acute coronary syndrome (ACS) in Finland during 1993-2007 and to create forecasts of the absolute numbers of ACS cases in the future, taking into account the aging of the population.
Community surveillance study and modelled forecasts of the future.
Two sets of population-based coronary event register data from Finland (FINAMI and the National Cardiovascular Disease Register (CVDR)). Bayesian age-period-cohort (APC) modelling.
24 905 observed ACS events in the FINAMI register and 364 137 in CVDR.
Observed trends of ACS events during 1993-2007, forecasted numbers of ACS cases, and the prevalence of ACS survivors until the year 2050.
In the FINAMI register, the average annual declines in age-standardised incidence of ACS were 1.6% (p
PubMed ID
23598542 View in PubMed
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Alcohol and incident heart failure among middle-aged and elderly men: cohort of Swedish men.

https://arctichealth.org/en/permalink/ahliterature265136
Source
Circ Heart Fail. 2015 May;8(3):422-7
Publication Type
Article
Date
May-2015
Author
Kirsten S Dorans
Elizabeth Mostofsky
Emily B Levitan
Niclas Håkansson
Alicja Wolk
Murray A Mittleman
Source
Circ Heart Fail. 2015 May;8(3):422-7
Date
May-2015
Language
English
Publication Type
Article
Keywords
Age Factors
Aged
Alcohol Drinking - adverse effects - epidemiology - mortality - therapy
Cause of Death
Heart Failure - diagnosis - epidemiology
Hospitalization
Humans
Incidence
Male
Markov Chains
Middle Aged
Monte Carlo Method
Multivariate Analysis
Proportional Hazards Models
Prospective Studies
Protective factors
Risk assessment
Risk factors
Sex Factors
Sweden - epidemiology
Time Factors
Abstract
Compared with no alcohol consumption, heavy alcohol intake is associated with a higher rate of heart failure (HF) whereas light-to-moderate intake may be associated with a lower rate. However, several prior studies did not exclude former drinkers, who may have changed alcohol consumption in response to diagnosis. This study aimed to investigate the association between alcohol intake and incident HF.
We conducted a prospective cohort study of 33 760 men aged 45 to 79 years with no HF, diabetes mellitus, or myocardial infarction at baseline participating in the Cohort of Swedish Men Study. We excluded former drinkers. At baseline, participants completed a food frequency questionnaire and reported other characteristics. HF was defined as hospitalization for or death from HF, ascertained by Swedish inpatient and cause-of-death records from January 1, 1998, through December 31, 2011. We constructed Cox proportional hazards models to estimate multivariable-adjusted incidence rate ratios. During follow-up, 2916 men were hospitalized for (n=2139) or died (n=777) of incident HF. There was a U-shaped relationship between total alcohol intake and incident HF (P=0.0004). There was a nadir at light-to-moderate alcohol intake: consuming 7 to
Notes
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PubMed ID
25872788 View in PubMed
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Alcohol use among American Indian high school youths from adolescence and young adulthood: a latent Markov model.

https://arctichealth.org/en/permalink/ahliterature92103
Source
J Stud Alcohol Drugs. 2008 Sep;69(5):666-75
Publication Type
Article
Date
Sep-2008
Author
Mitchell Christina M
Beals Janette
Whitesell Nancy Rumbaugh
Author Affiliation
American Indian and Alaska Native Programs, University of Colorado Denver, F800, P.O. Box 6508, Aurora, Colorado 80045-0508, USA. Christina.Mitchell@UCDenver.edu
Source
J Stud Alcohol Drugs. 2008 Sep;69(5):666-75
Date
Sep-2008
Language
English
Publication Type
Article
Keywords
Adolescent
Adult
Alcohol Drinking - epidemiology - ethnology - prevention & control
Data Collection
Female
Forecasting
Humans
Indians, North American - psychology
Longitudinal Studies
Male
Markov Chains
Substance-Related Disorders - epidemiology - ethnology
Time Factors
United States - epidemiology - ethnology
Abstract
OBJECTIVE: We explored patterns of alcohol use among American Indian youths as well as concurrent predictors and developmental outcomes 6 years later. METHOD: This study used six semi-annual waves of data collected across 3 years from 861 American Indian youths, ages 14-20 initially, from two western tribes. Using a latent Markov model, we examined patterns of change in latent states of adolescent alcohol use in the past 6 months, combining these states of alcohol use into three latent statuses that described patterns of change across the 3 years: abstainers, inconsistent drinkers, and consistent drinkers. We then explored how the latent statuses differed, both initially and in young adulthood (ages 20-26). RESULTS: Both alcohol use and nonuse were quite stable across time, although we also found evidence of change. Despite some rather troubling drinking patterns as teens, especially among consistent drinkers, most of the youths had achieved important tasks of young adulthood. But patterns of use during adolescence were related to greater levels of substance use in young adulthood. CONCLUSIONS: Latent Markov modeling provided a useful categorization of alcohol use that more finely differentiated those youths who would otherwise have been considered inconsistent drinkers. Findings also suggest that broad-based interventions during adolescence may not be the most important ones; instead, programs targeting later alcohol and other drug use may be a more strategic use of often limited resources.
PubMed ID
18781241 View in PubMed
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[Algorithmic support of the estimation of expenditures of medical services during dental treatment].

https://arctichealth.org/en/permalink/ahliterature193588
Source
Med Tekh. 2001 May-Jun;(3):44-8
Publication Type
Article

An algorithm for detecting high frequency copy number polymorphisms using SNP arrays.

https://arctichealth.org/en/permalink/ahliterature133202
Source
J Comput Biol. 2011 Aug;18(8):955-66
Publication Type
Article
Date
Aug-2011
Author
Bjarni V Halldórsson
Daníel F Gudbjartsson
Author Affiliation
School of Science and Engineering, Reykjavík University, Reykjavík, Iceland. bjarnivh@ru.is
Source
J Comput Biol. 2011 Aug;18(8):955-66
Date
Aug-2011
Language
English
Publication Type
Article
Keywords
Algorithms
Alleles
Base Pairing
Cluster analysis
Computational Biology - methods
DNA Copy Number Variations
Fluorescent Dyes - analysis
Gene Frequency
Genome, Human
Genome-Wide Association Study
Genotype
Humans
Iceland
Markov Chains
Microsatellite Repeats
Normal Distribution
Oligonucleotide Array Sequence Analysis - instrumentation - methods
Polymorphism, Single Nucleotide
Abstract
We present a general algorithm for the detection of genomic variants using the Illumina iSelect platform. The Illumina iSelect platform is designed to detect SNPs, but our algorithm allows for the detections of more general forms of variations, including copy number polymorphisms and microsatellites. The algorithm does not rely on a priori information of the type of polymorphism being studied and is designed to genotype call a large number of individuals simultaneously. The algorithm proceeds by initially normalizing intensity and correcting for batch effects. Then each marker is clustered using a modified Gaussian mixture model where we account for variances in the expression of an individuals and the variance measured in bead level intensities of a probe/marker pair. Finally, these clusters are used to determine genotypes. The algorithm was then run on a dataset of 35,000 Icelandic individuals.
PubMed ID
21728861 View in PubMed
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Analysis of cost effectiveness of screening Danish men aged 65 for abdominal aortic aneurysm.

https://arctichealth.org/en/permalink/ahliterature88585
Source
BMJ. 2009;338:b2243
Publication Type
Article
Date
2009
Author
Ehlers Lars
Overvad Kim
Sørensen Jan
Christensen Søren
Bech Merete
Kjølby Mette
Author Affiliation
Institute of Public Health, Aarhus University, Vennelyst Boulevard 6, 8000 Aarhus C, Denmark. le@folkesundhed.au.dk
Source
BMJ. 2009;338:b2243
Date
2009
Language
English
Publication Type
Article
Keywords
Aged
Aortic Aneurysm, Abdominal - economics - prevention & control - ultrasonography
Aortic Rupture - economics - prevention & control - ultrasonography
Cost-Benefit Analysis
Denmark
Humans
Male
Markov Chains
Mass Screening - economics
Quality of Life
Quality-Adjusted Life Years
Abstract
OBJECTIVE: To assess the cost effectiveness of screening men aged 65 for abdominal aortic aneurysm. DESIGN: Cost effectiveness analysis based on a probabilistic, enhanced economic decision analytical model from screening to death. POPULATION AND SETTING: Hypothetical population of men aged 65 invited (or not invited) for ultrasound screening in the Danish healthcare system. DATA SOURCES: Published results from randomised trials and observational epidemiological studies retrieved from electronic bibliographic databases, and supplementary data obtained from the Danish Vascular Registry. DATA SYNTHESIS: A hybrid decision tree and Markov model was developed to simulate the short term and long term effects of screening for abdominal aortic aneurysm compared with no systematic screening on clinical and cost effectiveness outcomes. Probabilistic sensitivity analyses using Monte Carlo simulation were carried out. Results were presented in a cost effectiveness acceptability curve, an expected value of perfect information curve, and a curve showing the expected (net) number of avoided deaths from abdominal aortic aneurysm over time after the introduction of screening. The model was validated by calibrating base case health outcomes and expected activity levels against evidence from the recent Cochrane review of screening for abdominal aortic aneurysm. RESULTS: The estimated costs per quality adjusted life year (QALY) gained discounted at 3% per year over a lifetime for costs and QALYs was pound43 485 (euro54,852; $71,160). At a willingness to pay threshold of pound30,000 the probability of screening for abdominal aortic aneurysm being cost effective was less than 30%. One way sensitivity analyses showed the incremental cost effectiveness ratio varying from pound32,640 to pound66,001 per QALY. CONCLUSION: Screening for abdominal aortic aneurysm does not seem to be cost effective. Further research is needed on long term quality of life outcomes and costs.
Notes
Comment In: BMJ. 2009;338:b218519553266
Comment In: BMJ. 2009;339:b304419638382
PubMed ID
19553267 View in PubMed
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314 records – page 1 of 32.