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Maximum likelihood estimate

Leslie A Brick, Marisa E Marraccini, Lauren Micalizzi, Chelsie E Benca-Bachman, Valerie S Knopik, Rohan H C Palmer
BACKGROUND: Suicide is the second leading cause of death among adolescents and young adults. Several studies have indicated significant genetic influences on suicide-related phenotypes and mounting evidence from neurobiological research has linked deficits in neurocognitive abilities to suicide phenotypes. The goal of the present study was to estimate the heritability of suicidal ideation (SI) in a large sample of adolescents and determine if SI is genetically correlated with neurocognitive functioning...
February 6, 2019: Journal of Affective Disorders
Carla Leal, Manuel Galea, Felipe Osorio
The concordance correlation coefficient (CCC) and the probability of agreement (PA) are two frequently used measures for evaluating the degree of agreement between measurements generated by two different methods. In this paper, we consider the CCC and the PA using the bivariate normal distribution for modeling the observations obtained by two measurement methods. The main aim of this paper is to develop diagnostic tools for the detection of those observations that are influential on the maximum likelihood estimators of the CCC and the PA using the local influence methodology but not based on the likelihood displacement...
February 15, 2019: Biometrical Journal. Biometrische Zeitschrift
Jonathan Zurawski, Bonnie I Glanz, Alicia Chua, Hrishikesh Lokhande, Dalia Rotstein, Howard Weiner, David Engler, Tanuja Chitnis, Brian C Healy
BACKGROUND: Although the expanded disability status scale (EDSS) is the most commonly used measure of disability for multiple sclerosis, measurement of disability accumulation is complex due to the unequal steps of the scale. OBJECTIVE: To estimate the time between EDSS scores in a large MS cohort from a single center and determine the impact of functional system scores on EDSS transitions. METHODS: 31,394 clinical visits with EDSS scores from 2054 subjects in the CLIMB longitudinal cohort study were included in our analysis...
February 5, 2019: Multiple Sclerosis and related Disorders
David Arbis, Vinayak V Dixit
The study employs a Quantal Response Equilibrium framework to model lane changing manoeuvres. Prior game theoretic studies in lane changing have pre-eminently assumed Nash equilibrium solutions with deterministic payoffs for actions. The study method involves developing expected utility models for drivers' merge and give-way decisions. These utility models incorporate explanatory variables representing driver trajectories during a lane changing manoeuvre. The model parameters are estimated using maximum likelihood on lane changing data at a freeway on-ramp using the NGSIM dataset...
February 11, 2019: Accident; Analysis and Prevention
Liang-Ching Lin, Li-Hsien Sun
In financial economics, a large number of models are developed based on the daily closing price. When using only the daily closing price to model the time series, we may discard valuable intra-daily information, such as maximum and minimum prices. In this study, we propose an interval time series model, including the daily maximum, minimum, and closing prices, and then apply the proposed model to forecast the entire interval. The likelihood function and the corresponding maximum likelihood estimates (MLEs) are obtained by stochastic differential equation and the Girsanov theorem...
2019: PloS One
Auston Sterling, Nicholas Rewkowski, Roberta L Klatzky, Ming C Lin
Modal sound synthesis has been used to create realistic sounds from rigid-body objects, but requires accurate real-world material parameters. These material parameters can be estimated from recorded sounds of an impacted object, but external factors can interfere with accurate parameter estimation. We present a novel technique for estimating the damping parameters of materials from recorded impact sounds that probabilistically models these external factors. We represent the combined effects of material damping, support damping, and sampling inaccuracies with a probabilistic generative model, then use maximum likelihood estimation to fit a damping model to recorded data...
February 14, 2019: IEEE Transactions on Visualization and Computer Graphics
Andrew J London
There are many sources of random and systematic error in composition quantification by atom probe microscopy, often, however, only statistical error is reported. Significantly larger errors can occur from the misidentification of ions and overlaps or interferences of peaks in the mass spectrum. These overlaps can be solved using maximum likelihood estimation (MLE), improving the accuracy of the result, but with an unknown effect on the precision. An analytical expression for the uncertainty of the MLE solution is presented and it is demonstrated to be much more accurate than the existing methods...
February 14, 2019: Microscopy and Microanalysis
Luisa Salazar-Vizcaya, Roger D Kouyos, Karin J Metzner, Kamila Caraballo Cortes, Jürg Böni, Cyril Shah, Jan Fehr, Dominique L Braun, Enos Bernasconi, Herbert A Mbunkah, Matthias Hoffmann, Niklaus Labhardt, Matthias Cavassini, Mathieu Rougemont, Huldrych F Günthard, Olivia Keiser, Andri Rauch
Background: Scale-up of direct-acting antiviral(DAA) therapy is expected to abate HCV incidence among HIV-positive men-who-have-sex-with-men(MSM). Treatment programs in neighbouring countries may influence each other's outcomes through international transmission. We aimed at classifying HCV infections in HIV-positive MSM as either domestically or internationally acquired, and at estimating how this classification changed over time. Methods: HCV subtype 1a (the most frequent subtype among MSM) genomes from 99 persons enrolled in the Swiss-HIV-Cohort-Study(SHCS) and diagnosed with replicating HCV infections between 1999 and 2016, were sequenced...
February 13, 2019: Journal of Infectious Diseases
Wenchao Ma, Wenjing Guo
Cognitive diagnosis models (CDMs) have been used as psychometric tools in educational assessments to estimate students' proficiency profiles. However, most CDMs assume that all students adopt the same strategy when approaching problems in an assessment, which may not be the case in practice. This study develops a generalized multiple-strategy CDM for dichotomous response data. The proposed model provides a unified framework to accommodate various condensation rules (e.g., conjunctive, disjunctive, and additive) and different strategy selection approaches (i...
February 12, 2019: British Journal of Mathematical and Statistical Psychology
Elizabeth O'Connor, Caitlyn A Senger, Michelle L Henninger, Erin Coppola, Bradley N Gaynes
Importance: Depression during pregnancy and the postpartum period is relatively common and can have adverse effects on both mother and child. Objective: To systematically review benefits and harms of primary care-relevant interventions to prevent perinatal depression, a major or minor depressive episode during pregnancy or up to 1 year after childbirth, to inform the US Preventive Services Task Force. Data Sources: MEDLINE, PubMED (for publisher-supplied records only), PsycINFO, and the Cochrane Central Register of Controlled Trials; surveillance through December 5, 2018...
February 12, 2019: JAMA: the Journal of the American Medical Association
Siriporn Tongsiri, Gilbert M Jeyaruban, Susanne Hermesch, Julius H J van der Werf, Li Li, Teerachai Chormai
Objective: Estimate genetic parameters, the rate of inbreeding, and the effect of inbreeding on growth and egg production traits of a Thai native chicken breed Lueng Hang Kao Kabinburi (LHKK) housed under intensive management under a tropical climate. Methods: Genetic parameters were estimated for weight measured at four weekly intervals from hatch (BWID) to 24 (BW24) weeks of age, as well as weight at first egg (BWFE), age at first egg (AFE), egg weight at first egg (EWFE) and total number of eggs produced during the first 17 weeks of lay (EN) using restricted maximum likelihood (REML)...
January 2, 2019: Asian-Australasian Journal of Animal Sciences
Manzoor Khan, Jake Olivier
Regression to the mean (RTM) occurs when subjects having relatively high or low measurements are remeasured and found closer to the population mean. This phenomenon can potentially lead to an inaccurate conclusion in a pre-post study design. Expressions are available for quantifying RTM when the distribution of pre and post observations are bivariate normal and bivariate Poisson. However, situations exist where the response variables are the number of successes in a fixed number of trials and follow the bivariate binomial distribution...
February 11, 2019: Statistics in Medicine
Lucas C Marinho, Liming Cai, Xiaoshan Duan, Brad R Ruhfel, Pedro Fiaschi, André M Amorim, Cássio van den Berg, Charles C Davis
Clusieae is an exclusively Neotropical tribe in the family Clusiaceae sensu stricto. Although tribes within Clusiaceae are morphologically and phylogenetically well-delimited, resolution among genera within these tribes remains elusive. The tribe Clusieae includes an estimated ∼500 species distributed among five genera: Chrysochlamys, Clusia, Dystovomita, Tovomita, and Tovomitopsis. In this study, we used nearly complete plastid genomes from 30 exemplar Clusieae species representing all genera recognized, plus two outgroups to infer the phylogeny of the tribe using Maximum Likelihood and Bayesian Inference...
February 8, 2019: Molecular Phylogenetics and Evolution
Il Do Ha, Liming Xiang, Mengjiao Peng, Jong-Hyeon Jeong, Youngjo Lee
In the semi-competing risks situation where only a terminal event censors a non-terminal event, observed event times can be correlated. Recently, frailty models with an arbitrary baseline hazard have been studied for the analysis of such semi-competing risks data. However, their maximum likelihood estimator can be substantially biased in the finite samples. In this paper, we propose effective modifications to reduce such bias using the hierarchical likelihood. We also investigate the relationship between marginal and hierarchical likelihood approaches...
February 7, 2019: Lifetime Data Analysis
Eveline A J van Rein, Rogier van der Sluijs, Frank J Voskens, Koen W W Lansink, R Marijn Houwert, Rob A Lichtveld, Mariska A de Jongh, Marcel G W Dijkgraaf, Howard R Champion, Frank J P Beeres, Luke P H Leenen, Mark van Heijl
Importance: Prehospital trauma triage protocols are used worldwide to get the right patient to the right hospital and thereby improve the chance of survival and avert lifelong disabilities. The American College of Surgeons Committee on Trauma set target levels for undertriage rates of less than 5%. None of the existing triage protocols has been able to achieve this target in isolation. Objective: To develop and validate a new prehospital trauma triage protocol to improve current triage rates...
February 6, 2019: JAMA Surgery
P Mdlongwa, B O Oluyede, A K A Amey, A F Fagbamigbe, B Makubate
We develop the new Kumaraswamy Log-Logistic Weibull (KLLoGW) distribution by combining the Kumaraswamy and Log-logistic Weibull distributions. This new model is flexible for modelling lifetime data. Some statistical properties including quantile function, hazard rate function, moments and conditional moments are presented. Model parameters are estimated via the method of maximum likelihood and a Monte Carlo simulation study conducted to assess the accuracy of the estimates. Finally, the model is applied to a real dataset...
January 2019: Heliyon
Qun Gao, Yujie Ben, Zhaomin Dong, Jianying Hu
Constant elimination half-life is usually used in first-order one-compartment pharmacokinetic models to assess human exposure to dioxin-like polychlorinated biphenyls (PCBs). However, hepatic clearance rates are usually lower for elders than for young people. In this study, levels of 12 dioxin-like PCBs were determined in blood samples collected in 2012 from 305 individuals from the general population. We estimated the historical daily intake of dioxin-like PCBs for individuals with a validated annual exponential decay function...
January 31, 2019: Chemosphere
Zhiyang Yao, Yongshun Xiao, Zhiqiang Chen, Bo Wang, Qinhan Hou
Prompt gamma ray (PG) imaging based on Compton camera (CC) is promising to realize in vivo verification during the proton therapy. However, the finite spatial and energy resolution of current CC, as well as the Doppler broaden effect, degrade the quality and resolution of PG images. In addition, due to the inherent geometrical complexity of Compton camera data, PG imaging can be time-consuming and difficult to reconstruct in real-time, while using standard techniques such as filtered back-projection or maximum likelihood-expectation maximization...
February 4, 2019: Scientific Reports
Robert C Jadin, Christopher Blair, Michael J Jowers, Anthony Carmona, John C Murphy
The Brown Vine Snake, Oxybelis aeneus, is considered a single species despite the fact its distribution covers an estimated 10% of the Earth's land surface, inhabiting a variety of ecosystems throughout North, Central, and South America and is distributed across numerous biogeographic barriers. Here we assemble a multilocus molecular dataset (i.e. cyt b, ND4, cmos, PRLR) derived from Middle American populations to examine for the first time the evolutionary history of Oxybelis and test for evidence of cryptic lineages using Bayesian and maximum likelihood criteria...
February 1, 2019: Molecular Phylogenetics and Evolution
Caleb H Miles, Maya Petersen, Mark J van der Laan
The assumption that no subject's exposure affects another subject's outcome, known as the no-interference assumption, has long held a foundational position in the study of causal inference. However, this assumption may be violated in many settings, and in recent years has been relaxed considerably. Often this has been achieved with either the aid of a known underlying network, or the assumption that the population can be partitioned into separate groups, between which there is no interference, and within which each subject's outcome may be affected by all the other subjects in the group via the proportion exposed (the stratified interference assumption)...
February 4, 2019: Biometrics
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