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Imputation and post-selection inference in models with missing data: An application to colorectal cancer surveillance guidelines

Lin Liu, Yuqi Qiu, Loki Natarajan, Karen Messer.

Source: The Annals of Applied Statistics, Volume 13, Number 3, 1370--1396.

Abstract:
It is common to encounter missing data among the potential predictor variables in the setting of model selection. For example, in a recent study we attempted to improve the US guidelines for risk stratification after screening colonoscopy ( Cancer Causes Control 27 (2016) 1175–1185), with the aim to help reduce both overuse and underuse of follow-on surveillance colonoscopy. The goal was to incorporate selected additional informative variables into a neoplasia risk-prediction model, going beyond the three currently established risk factors, using a large dataset pooled from seven different prospective studies in North America. Unfortunately, not all candidate variables were collected in all studies, so that one or more important potential predictors were missing on over half of the subjects. Thus, while variable selection was a main focus of the study, it was necessary to address the substantial amount of missing data. Multiple imputation can effectively address missing data, and there are also good approaches to incorporate the variable selection process into model-based confidence intervals. However, there is not consensus on appropriate methods of inference which address both issues simultaneously. Our goal here is to study the properties of model-based confidence intervals in the setting of imputation for missing data followed by variable selection. We use both simulation and theory to compare three approaches to such post-imputation-selection inference: a multiple-imputation approach based on Rubin’s Rules for variance estimation ( Comput. Statist. Data Anal. 71 (2014) 758–770); a single imputation-selection followed by bootstrap percentile confidence intervals; and a new bootstrap model-averaging approach presented here, following Efron ( J. Amer. Statist. Assoc. 109 (2014) 991–1007). We investigate relative strengths and weaknesses of each method. The “Rubin’s Rules” multiple imputation estimator can have severe undercoverage, and is not recommended. The imputation-selection estimator with bootstrap percentile confidence intervals works well. The bootstrap-model-averaged estimator, with the “Efron’s Rules” estimated variance, may be preferred if the true effect sizes are moderate. We apply these results to the colorectal neoplasia risk-prediction problem which motivated the present work.




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Local law and Tracy–Widom limit for sparse stochastic block models

Jong Yun Hwang, Ji Oon Lee, Wooseok Yang.

Source: Bernoulli, Volume 26, Number 3, 2400--2435.

Abstract:
We consider the spectral properties of sparse stochastic block models, where $N$ vertices are partitioned into $K$ balanced communities. Under an assumption that the intra-community probability and inter-community probability are of similar order, we prove a local semicircle law up to the spectral edges, with an explicit formula on the deterministic shift of the spectral edge. We also prove that the fluctuation of the extremal eigenvalues is given by the GOE Tracy–Widom law after rescaling and centering the entries of sparse stochastic block models. Applying the result to sparse stochastic block models, we rigorously prove that there is a large gap between the outliers and the spectral edge without centering.




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Local differential privacy: Elbow effect in optimal density estimation and adaptation over Besov ellipsoids

Cristina Butucea, Amandine Dubois, Martin Kroll, Adrien Saumard.

Source: Bernoulli, Volume 26, Number 3, 1727--1764.

Abstract:
We address the problem of non-parametric density estimation under the additional constraint that only privatised data are allowed to be published and available for inference. For this purpose, we adopt a recent generalisation of classical minimax theory to the framework of local $alpha$-differential privacy and provide a lower bound on the rate of convergence over Besov spaces $mathcal{B}^{s}_{pq}$ under mean integrated $mathbb{L}^{r}$-risk. This lower bound is deteriorated compared to the standard setup without privacy, and reveals a twofold elbow effect. In order to fulfill the privacy requirement, we suggest adding suitably scaled Laplace noise to empirical wavelet coefficients. Upper bounds within (at most) a logarithmic factor are derived under the assumption that $alpha$ stays bounded as $n$ increases: A linear but non-adaptive wavelet estimator is shown to attain the lower bound whenever $pgeq r$ but provides a slower rate of convergence otherwise. An adaptive non-linear wavelet estimator with appropriately chosen smoothing parameters and thresholding is shown to attain the lower bound within a logarithmic factor for all cases.




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On the eigenproblem for Gaussian bridges

Pavel Chigansky, Marina Kleptsyna, Dmytro Marushkevych.

Source: Bernoulli, Volume 26, Number 3, 1706--1726.

Abstract:
Spectral decomposition of the covariance operator is one of the main building blocks in the theory and applications of Gaussian processes. Unfortunately, it is notoriously hard to derive in a closed form. In this paper, we consider the eigenproblem for Gaussian bridges. Given a base process, its bridge is obtained by conditioning the trajectories to start and terminate at the given points. What can be said about the spectrum of a bridge, given the spectrum of its base process? We show how this question can be answered asymptotically for a family of processes, including the fractional Brownian motion.




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Stable processes conditioned to hit an interval continuously from the outside

Leif Döring, Philip Weissmann.

Source: Bernoulli, Volume 26, Number 2, 980--1015.

Abstract:
Conditioning stable Lévy processes on zero probability events recently became a tractable subject since several explicit formulas emerged from a deep analysis using the Lamperti transformations for self-similar Markov processes. In this article, we derive new harmonic functions and use them to explain how to condition stable processes to hit continuously a compact interval from the outside.




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Recurrence of multidimensional persistent random walks. Fourier and series criteria

Peggy Cénac, Basile de Loynes, Yoann Offret, Arnaud Rousselle.

Source: Bernoulli, Volume 26, Number 2, 858--892.

Abstract:
The recurrence and transience of persistent random walks built from variable length Markov chains are investigated. It turns out that these stochastic processes can be seen as Lévy walks for which the persistence times depend on some internal Markov chain: they admit Markov random walk skeletons. A recurrence versus transience dichotomy is highlighted. Assuming the positive recurrence of the driving chain, a sufficient Fourier criterion for the recurrence, close to the usual Chung–Fuchs one, is given and a series criterion is derived. The key tool is the Nagaev–Guivarc’h method. Finally, we focus on particular two-dimensional persistent random walks, including directionally reinforced random walks, for which necessary and sufficient Fourier and series criteria are obtained. Inspired by ( Adv. Math. 208 (2007) 680–698), we produce a genuine counterexample to the conjecture of ( Adv. Math. 117 (1996) 239–252). As for the one-dimensional case studied in ( J. Theoret. Probab. 31 (2018) 232–243), it is easier for a persistent random walk than its skeleton to be recurrent. However, such examples are much more difficult to exhibit in the higher dimensional context. These results are based on a surprisingly novel – to our knowledge – upper bound for the Lévy concentration function associated with symmetric distributions.




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Needles and straw in a haystack: Robust confidence for possibly sparse sequences

Eduard Belitser, Nurzhan Nurushev.

Source: Bernoulli, Volume 26, Number 1, 191--225.

Abstract:
In the general signal$+$noise (allowing non-normal, non-independent observations) model, we construct an empirical Bayes posterior which we then use for uncertainty quantification for the unknown, possibly sparse, signal. We introduce a novel excessive bias restriction (EBR) condition, which gives rise to a new slicing of the entire space that is suitable for uncertainty quantification. Under EBR and some mild exchangeable exponential moment condition on the noise, we establish the local (oracle) optimality of the proposed confidence ball. Without EBR, we propose another confidence ball of full coverage, but its radius contains an additional $sigma n^{1/4}$-term. In passing, we also get the local optimal results for estimation , posterior contraction problems, and the problem of weak recovery of sparsity structure . Adaptive minimax results (also for the estimation and posterior contraction problems) over various sparsity classes follow from our local results.




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From the coalfields of Somerset to the Adelaide Hills and beyond : the story of the Hewish Family : three centuries of one family's journey through time / Maureen Brown.

Hewish Henry -- Family.




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No turning back : stories of our ancestors / by David Gambling.

Gambling (Family)




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Living through English history : stories of the Urlwin, Brittridge, Vasper, Partridge and Ellerby families / Janet McLeod.

Urlwin (Family).




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How States, Assessment Companies Can Work Together Amid Coronavirus Testing Cancellations

Scott Marion, who consults states on testing, talks about why it's important for vendors and public officials to work cooperatively in renegotiating contracts amid assessment cancellations caused by COVID-19.

The post How States, Assessment Companies Can Work Together Amid Coronavirus Testing Cancellations appeared first on Market Brief.




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Economists Expect Huge Future Earnings Loss for Students Missing School Due to COVID-19

Members of the future American workforce could see losses of earnings that add up to trillions of dollars, depending on how long coronavirus-related school closures persist.

The post Economists Expect Huge Future Earnings Loss for Students Missing School Due to COVID-19 appeared first on Market Brief.




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ACT and Teachers’ Union Partner to Provide Remote Learning Resources Amid Pandemic

ACT and the American Federation of Teachers are partnering to provide free resources as educators increasingly switch to distance learning amid the COVID-19 pandemic.

The post ACT and Teachers’ Union Partner to Provide Remote Learning Resources Amid Pandemic appeared first on Market Brief.




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As States’ Budgets Reel During COVID-19, Districts to Feel the Wrath

State funding for K-12 is likely to fall sharply, though districts could look to protect essentials like distance-learning support and professional development, says school finance expert Mike Griffith.

The post As States’ Budgets Reel During COVID-19, Districts to Feel the Wrath appeared first on Market Brief.




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Glass stereoscopic slides of Gallipoli, May 1915 / photographed by Charles Snodgrass Ryan




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Smart research for HSC students: Citing your work and avoiding plagiarism

This session brings together the key resources for HSC subjects, including those that are useful for studying Advanced and Extension courses.




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3 NY children die from syndrome possibly linked to COVID-19

Three children have now died in New York state from a possible complication from the coronavirus involving swollen blood vessels and heart problems, Gov. Andrew Cuomo said Saturday. At least 73 children in New York have been diagnosed with symptoms similar to Kawasaki disease — a rare inflammatory condition in children — and toxic shock syndrome.





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Anarchy in Venezuela's jails laid bare by massacre over food

Three weeks before he was shot dead, Miguel Calderon, an inmate in the lawless Los Llanos jail on Venezuela's central plains, sent a voice message to his father. Like many of the prisoners in Venezuela's overcrowded and violent penitentiaries, Los Llanos's 4,000 inmates normally subsist on food relatives bring them. The guards, desperate themselves amid national shortages, began stealing the little food getting behind bars, inmates said, forcing some prisoners to turn to eating stray animals.





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Boeing says it's about to start building the 737 Max plane again in the middle of the coronavirus pandemic, even though it already has more planes than it can deliver

Boeing CEO Dave Calhoun said the company was aiming to resume production this month, despite the ongoing grounding and coronavirus pandemic.





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As Trump returns to the road, some Democrats want to bust Biden out of his basement

While President Donald Trump traveled to the battleground state of Arizona this week, his Democratic opponent for the White House, Joe Biden, campaigned from his basement as he has done throughout the coronavirus pandemic. The freeze on in-person campaigning during the outbreak has had an upside for Biden, giving the former vice president more time to court donors and shielding him from on-the-trail gaffes. "I personally would like to see him out more because he's in his element when he's meeting people," said Tom Sacks-Wilner, a fundraiser for Biden who is on the campaign's finance committee.





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'We Cannot Police Our Way Out of a Pandemic.' Experts, Police Union Say NYPD Should Not Be Enforcing Social Distance Rules Amid COVID-19

The New York City police department (NYPD) is conducting an internal investigation into a May 2 incident involving the violent arrests of multiple people, allegedly members of a group who were not social distancing





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‘Selfish, tribal and divided’: Barack Obama warns of changes to American way of life in leaked audio slamming Trump administration

Barack Obama said the “rule of law is at risk” following the justice department’s decision to drop charges against former Trump advisor Mike Flynn, as he issued a stark warning about the long-term impact on the American way of life by his successor.





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Almost 12,000 meatpacking and food plant workers have reportedly contracted COVID-19. At least 48 have died.

The infections and deaths are spread across roughly two farms and 189 meat and processed food factories.





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The accusation against Joe Biden has Democrats rediscovering the value of due process

Some Democrats took "Believe Women" literally until Joe Biden was accused. Now they're relearning that guilt-by-accusation doesn't serve justice.





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Scalable Bayesian Inference for the Inverse Temperature of a Hidden Potts Model

Matthew Moores, Geoff Nicholls, Anthony Pettitt, Kerrie Mengersen.

Source: Bayesian Analysis, Volume 15, Number 1, 1--27.

Abstract:
The inverse temperature parameter of the Potts model governs the strength of spatial cohesion and therefore has a major influence over the resulting model fit. A difficulty arises from the dependence of an intractable normalising constant on the value of this parameter and thus there is no closed-form solution for sampling from the posterior distribution directly. There is a variety of computational approaches for sampling from the posterior without evaluating the normalising constant, including the exchange algorithm and approximate Bayesian computation (ABC). A serious drawback of these algorithms is that they do not scale well for models with a large state space, such as images with a million or more pixels. We introduce a parametric surrogate model, which approximates the score function using an integral curve. Our surrogate model incorporates known properties of the likelihood, such as heteroskedasticity and critical temperature. We demonstrate this method using synthetic data as well as remotely-sensed imagery from the Landsat-8 satellite. We achieve up to a hundredfold improvement in the elapsed runtime, compared to the exchange algorithm or ABC. An open-source implementation of our algorithm is available in the R package bayesImageS .




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Bayes Factors for Partially Observed Stochastic Epidemic Models

Muteb Alharthi, Theodore Kypraios, Philip D. O’Neill.

Source: Bayesian Analysis, Volume 14, Number 3, 927--956.

Abstract:
We consider the problem of model choice for stochastic epidemic models given partial observation of a disease outbreak through time. Our main focus is on the use of Bayes factors. Although Bayes factors have appeared in the epidemic modelling literature before, they can be hard to compute and little attention has been given to fundamental questions concerning their utility. In this paper we derive analytic expressions for Bayes factors given complete observation through time, which suggest practical guidelines for model choice problems. We adapt the power posterior method for computing Bayes factors so as to account for missing data and apply this approach to partially observed epidemics. For comparison, we also explore the use of a deviance information criterion for missing data scenarios. The methods are illustrated via examples involving both simulated and real data.




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Alleviating Spatial Confounding for Areal Data Problems by Displacing the Geographical Centroids

Marcos Oliveira Prates, Renato Martins Assunção, Erica Castilho Rodrigues.

Source: Bayesian Analysis, Volume 14, Number 2, 623--647.

Abstract:
Spatial confounding between the spatial random effects and fixed effects covariates has been recently discovered and showed that it may bring misleading interpretation to the model results. Techniques to alleviate this problem are based on decomposing the spatial random effect and fitting a restricted spatial regression. In this paper, we propose a different approach: a transformation of the geographic space to ensure that the unobserved spatial random effect added to the regression is orthogonal to the fixed effects covariates. Our approach, named SPOCK, has the additional benefit of providing a fast and simple computational method to estimate the parameters. Also, it does not constrain the distribution class assumed for the spatial error term. A simulation study and real data analyses are presented to better understand the advantages of the new method in comparison with the existing ones.




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Risk Models for Breast Cancer and Their Validation

Adam R. Brentnall, Jack Cuzick.

Source: Statistical Science, Volume 35, Number 1, 14--30.

Abstract:
Strategies to prevent cancer and diagnose it early when it is most treatable are needed to reduce the public health burden from rising disease incidence. Risk assessment is playing an increasingly important role in targeting individuals in need of such interventions. For breast cancer many individual risk factors have been well understood for a long time, but the development of a fully comprehensive risk model has not been straightforward, in part because there have been limited data where joint effects of an extensive set of risk factors may be estimated with precision. In this article we first review the approach taken to develop the IBIS (Tyrer–Cuzick) model, and describe recent updates. We then review and develop methods to assess calibration of models such as this one, where the risk of disease allowing for competing mortality over a long follow-up time or lifetime is estimated. The breast cancer risk model model and calibration assessment methods are demonstrated using a cohort of 132,139 women attending mammography screening in the State of Washington, USA.




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'Smoking is slow-motion suicide' / Biman Mullick.

London (33 Stillness Rd, London, SE23 ING) : Cleanair, Campaign for a Smoke-free Environment, [198-?]




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The hidden holocaust.

[London?], [199-?]




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[Silhouette of a pregant woman smoking with death skull inside womb, 29 January 1994] / design: Biman Mullick.

London, [29 January 1994]




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Healthy Holiday Gift Ideas for Women

Treat the babe in your life to one (or two or three) of these indulgent gifts.




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Taylor Swift, Hailey Bieber, and Tons of Other Celebs’ Favorite Leggings Are on Sale Ahead of Black Friday

Here’s where you can snag their Alo Yoga Moto leggings for less.




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Gabrielle Union's Mesmerizing Tie Dye Activewear Set Is On Sale for Black Friday

The rainbow sports bra and leggings set from Splits59 is a must-have for anyone craving a pop of color in their workout wardrobe.




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These Nordstrom Cyber Monday Deals Are Giving Black Friday a Run for Its Money

This is not a drill: You can get up to 50% off at Nordstrom right now.




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The Comfy Sneakers That Kate Middleton, Kelly Ripa, and More Celebs Love Are on Sale at Amazon

Keep your feet comfy and your wallet fat.




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Metacognitive Mechanisms Underlying Lucid Dreaming

Elisa Filevich
Jan 21, 2015; 35:1082-1088
BehavioralSystemsCognitive




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Axonal ramifications of hippocampal Ca1 pyramidal cells

WD Knowles
Nov 1, 1981; 1:1236-1241
Articles




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{Delta}9-Tetrahydrocannabinol and Cannabinol Activate Capsaicin-Sensitive Sensory Nerves via a CB1 and CB2 Cannabinoid Receptor-Independent Mechanism

Peter M. Zygmunt
Jun 1, 2002; 22:4720-4727
Behavioral




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Dural Calcitonin Gene-Related Peptide Produces Female-Specific Responses in Rodent Migraine Models

Amanda Avona
May 29, 2019; 39:4323-4331
Systems/Circuits




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Circuit Stability to Perturbations Reveals Hidden Variability in the Balance of Intrinsic and Synaptic Conductances

Sebastian Onasch
Apr 15, 2020; 40:3186-3202
Systems/Circuits




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Social Laughter Triggers Endogenous Opioid Release in Humans

Sandra Manninen
Jun 21, 2017; 37:6125-6131
BehavioralSystemsCognitive




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Oscillatory Coupling of Hippocampal Pyramidal Cells and Interneurons in the Behaving Rat

Jozsef Csicsvari
Jan 1, 1999; 19:274-287
Articles




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Evidence for multiple AMPA receptor complexes in hippocampal CA1/CA2 neurons

RJ Wenthold
Mar 15, 1996; 16:1982-1989
Articles




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Neurodegeneration induced by beta-amyloid peptides in vitro: the role of peptide assembly state

CJ Pike
Apr 1, 1993; 13:1676-1687
Articles




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Dendritic spines of CA 1 pyramidal cells in the rat hippocampus: serial electron microscopy with reference to their biophysical characteristics

KM Harris
Aug 1, 1989; 9:2982-2997
Articles




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A selective impairment of motion perception following lesions of the middle temporal visual area (MT)

WT Newsome
Jun 1, 1988; 8:2201-2211
Articles




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Mice Deficient in Cellular Glutathione Peroxidase Show Increased Vulnerability to Malonate, 3-Nitropropionic Acid, and 1-Methyl-4-Phenyl-1,2,5,6-Tetrahydropyridine

Peter Klivenyi
Jan 1, 2000; 20:1-7
Cellular




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High-Level Neuronal Expression of A{beta}1-42 in Wild-Type Human Amyloid Protein Precursor Transgenic Mice: Synaptotoxicity without Plaque Formation

Lennart Mucke
Jun 1, 2000; 20:4050-4058
Cellular




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La fiducia: l'anello mancante delle criptovalute attuali

Italian translation of the Press Release on the pre-release of two special chapters of the Annual Economic Report of the BIS, 17 June 2018. Trust is the missing link in today's cryptocurrencies - Cryptocurrencies' model of generating trust limits their potential to replace conventional money, the Bank for International Settlements (BIS) writes in its Annual Economic Report (AER), a new title launched this year.