w Scaling limits for super-replication with transient price impact By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Peter Bank, Yan Dolinsky. Source: Bernoulli, Volume 26, Number 3, 2176--2201.Abstract: We prove a scaling limit theorem for the super-replication cost of options in a Cox–Ross–Rubinstein binomial model with transient price impact. The correct scaling turns out to keep the market depth parameter constant while resilience over fixed periods of time grows in inverse proportion with the duration between trading times. For vanilla options, the scaling limit is found to coincide with the one obtained by PDE-methods in ( Math. Finance 22 (2012) 250–276) for models with purely temporary price impact. These models are a special case of our framework and so our probabilistic scaling limit argument allows one to expand the scope of the scaling limit result to path-dependent options. Full Article
w Noncommutative Lebesgue decomposition and contiguity with applications in quantum statistics By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Akio Fujiwara, Koichi Yamagata. Source: Bernoulli, Volume 26, Number 3, 2105--2142.Abstract: We herein develop a theory of contiguity in the quantum domain based upon a novel quantum analogue of the Lebesgue decomposition. The theory thus formulated is pertinent to the weak quantum local asymptotic normality introduced in the previous paper [Yamagata, Fujiwara, and Gill, Ann. Statist. 41 (2013) 2197–2217], yielding substantial enlargement of the scope of quantum statistics. Full Article
w Functional weak limit theorem for a local empirical process of non-stationary time series and its application By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Ulrike Mayer, Henryk Zähle, Zhou Zhou. Source: Bernoulli, Volume 26, Number 3, 1891--1911.Abstract: We derive a functional weak limit theorem for a local empirical process of a wide class of piece-wise locally stationary (PLS) time series. The latter result is applied to derive the asymptotics of weighted empirical quantiles and weighted V-statistics of non-stationary time series. The class of admissible underlying time series is illustrated by means of PLS linear processes and PLS ARCH processes. Full Article
w Kernel and wavelet density estimators on manifolds and more general metric spaces By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Galatia Cleanthous, Athanasios G. Georgiadis, Gerard Kerkyacharian, Pencho Petrushev, Dominique Picard. Source: Bernoulli, Volume 26, Number 3, 1832--1862.Abstract: We consider the problem of estimating the density of observations taking values in classical or nonclassical spaces such as manifolds and more general metric spaces. Our setting is quite general but also sufficiently rich in allowing the development of smooth functional calculus with well localized spectral kernels, Besov regularity spaces, and wavelet type systems. Kernel and both linear and nonlinear wavelet density estimators are introduced and studied. Convergence rates for these estimators are established and discussed. Full Article
w Optimal functional supervised classification with separation condition By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Sébastien Gadat, Sébastien Gerchinovitz, Clément Marteau. Source: Bernoulli, Volume 26, Number 3, 1797--1831.Abstract: We consider the binary supervised classification problem with the Gaussian functional model introduced in ( Math. Methods Statist. 22 (2013) 213–225). Taking advantage of the Gaussian structure, we design a natural plug-in classifier and derive a family of upper bounds on its worst-case excess risk over Sobolev spaces. These bounds are parametrized by a separation distance quantifying the difficulty of the problem, and are proved to be optimal (up to logarithmic factors) through matching minimax lower bounds. Using the recent works of (In Advances in Neural Information Processing Systems (2014) 3437–3445 Curran Associates) and ( Ann. Statist. 44 (2016) 982–1009), we also derive a logarithmic lower bound showing that the popular $k$-nearest neighbors classifier is far from optimality in this specific functional setting. Full Article
w A fast algorithm with minimax optimal guarantees for topic models with an unknown number of topics By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Xin Bing, Florentina Bunea, Marten Wegkamp. Source: Bernoulli, Volume 26, Number 3, 1765--1796.Abstract: Topic models have become popular for the analysis of data that consists in a collection of n independent multinomial observations, with parameters $N_{i}inmathbb{N}$ and $Pi_{i}in[0,1]^{p}$ for $i=1,ldots,n$. The model links all cell probabilities, collected in a $p imes n$ matrix $Pi$, via the assumption that $Pi$ can be factorized as the product of two nonnegative matrices $Ain[0,1]^{p imes K}$ and $Win[0,1]^{K imes n}$. Topic models have been originally developed in text mining, when one browses through $n$ documents, based on a dictionary of $p$ words, and covering $K$ topics. In this terminology, the matrix $A$ is called the word-topic matrix, and is the main target of estimation. It can be viewed as a matrix of conditional probabilities, and it is uniquely defined, under appropriate separability assumptions, discussed in detail in this work. Notably, the unique $A$ is required to satisfy what is commonly known as the anchor word assumption, under which $A$ has an unknown number of rows respectively proportional to the canonical basis vectors in $mathbb{R}^{K}$. The indices of such rows are referred to as anchor words. Recent computationally feasible algorithms, with theoretical guarantees, utilize constructively this assumption by linking the estimation of the set of anchor words with that of estimating the $K$ vertices of a simplex. This crucial step in the estimation of $A$ requires $K$ to be known, and cannot be easily extended to the more realistic set-up when $K$ is unknown. This work takes a different view on anchor word estimation, and on the estimation of $A$. We propose a new method of estimation in topic models, that is not a variation on the existing simplex finding algorithms, and that estimates $K$ from the observed data. We derive new finite sample minimax lower bounds for the estimation of $A$, as well as new upper bounds for our proposed estimator. We describe the scenarios where our estimator is minimax adaptive. Our finite sample analysis is valid for any $n,N_{i},p$ and $K$, and both $p$ and $K$ are allowed to increase with $n$, a situation not handled well by previous analyses. We complement our theoretical results with a detailed simulation study. We illustrate that the new algorithm is faster and more accurate than the current ones, although we start out with a computational and theoretical disadvantage of not knowing the correct number of topics $K$, while we provide the competing methods with the correct value in our simulations. Full Article
w Local differential privacy: Elbow effect in optimal density estimation and adaptation over Besov ellipsoids By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT 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. Full Article
w Sojourn time dimensions of fractional Brownian motion By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Ivan Nourdin, Giovanni Peccati, Stéphane Seuret. Source: Bernoulli, Volume 26, Number 3, 1619--1634.Abstract: We describe the size of the sets of sojourn times $E_{gamma }={tgeq 0:|B_{t}|leq t^{gamma }}$ associated with a fractional Brownian motion $B$ in terms of various large scale dimensions. Full Article
w On the probability distribution of the local times of diagonally operator-self-similar Gaussian fields with stationary increments By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Kamran Kalbasi, Thomas Mountford. Source: Bernoulli, Volume 26, Number 2, 1504--1534.Abstract: In this paper, we study the local times of vector-valued Gaussian fields that are ‘diagonally operator-self-similar’ and whose increments are stationary. Denoting the local time of such a Gaussian field around the spatial origin and over the temporal unit hypercube by $Z$, we show that there exists $lambdain(0,1)$ such that under some quite weak conditions, $lim_{n ightarrow+infty}frac{sqrt[n]{mathbb{E}(Z^{n})}}{n^{lambda}}$ and $lim_{x ightarrow+infty}frac{-logmathbb{P}(Z>x)}{x^{frac{1}{lambda}}}$ both exist and are strictly positive (possibly $+infty$). Moreover, we show that if the underlying Gaussian field is ‘strongly locally nondeterministic’, the above limits will be finite as well. These results are then applied to establish similar statements for the intersection local times of diagonally operator-self-similar Gaussian fields with stationary increments. Full Article
w Limit theorems for long-memory flows on Wiener chaos By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Shuyang Bai, Murad S. Taqqu. Source: Bernoulli, Volume 26, Number 2, 1473--1503.Abstract: We consider a long-memory stationary process, defined not through a moving average type structure, but by a flow generated by a measure-preserving transform and by a multiple Wiener–Itô integral. The flow is described using a notion of mixing for infinite-measure spaces introduced by Krickeberg (In Proc. Fifth Berkeley Sympos. Math. Statist. and Probability (Berkeley, Calif., 1965/66), Vol. II: Contributions to Probability Theory, Part 2 (1967) 431–446 Univ. California Press). Depending on the interplay between the spreading rate of the flow and the order of the multiple integral, one can recover known central or non-central limit theorems, and also obtain joint convergence of multiple integrals of different orders. Full Article
w The moduli of non-differentiability for Gaussian random fields with stationary increments By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Wensheng Wang, Zhonggen Su, Yimin Xiao. Source: Bernoulli, Volume 26, Number 2, 1410--1430.Abstract: We establish the exact moduli of non-differentiability of Gaussian random fields with stationary increments. As an application of the result, we prove that the uniform Hölder condition for the maximum local times of Gaussian random fields with stationary increments obtained in Xiao (1997) is optimal. These results are applicable to fractional Riesz–Bessel processes and stationary Gaussian random fields in the Matérn and Cauchy classes. Full Article
w Stratonovich stochastic differential equation with irregular coefficients: Girsanov’s example revisited By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Ilya Pavlyukevich, Georgiy Shevchenko. Source: Bernoulli, Volume 26, Number 2, 1381--1409.Abstract: In this paper, we study the Stratonovich stochastic differential equation $mathrm{d}X=|X|^{alpha }circ mathrm{d}B$, $alpha in (-1,1)$, which has been introduced by Cherstvy et al. ( New J. Phys. 15 (2013) 083039) in the context of analysis of anomalous diffusions in heterogeneous media. We determine its weak and strong solutions, which are homogeneous strong Markov processes spending zero time at $0$: for $alpha in (0,1)$, these solutions have the form egin{equation*}X_{t}^{ heta }=((1-alpha)B_{t}^{ heta })^{1/(1-alpha )},end{equation*} where $B^{ heta }$ is the $ heta $-skew Brownian motion driven by $B$ and starting at $frac{1}{1-alpha }(X_{0})^{1-alpha }$, $ heta in [-1,1]$, and $(x)^{gamma }=|x|^{gamma }operatorname{sign}x$; for $alpha in (-1,0]$, only the case $ heta =0$ is possible. The central part of the paper consists in the proof of the existence of a quadratic covariation $[f(B^{ heta }),B]$ for a locally square integrable function $f$ and is based on the time-reversion technique for Markovian diffusions. Full Article
w On stability of traveling wave solutions for integro-differential equations related to branching Markov processes By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Pasha Tkachov. Source: Bernoulli, Volume 26, Number 2, 1354--1380.Abstract: The aim of this paper is to prove stability of traveling waves for integro-differential equations connected with branching Markov processes. In other words, the limiting law of the left-most particle of a (time-continuous) branching Markov process with a Lévy non-branching part is demonstrated. The key idea is to approximate the branching Markov process by a branching random walk and apply the result of Aïdékon [ Ann. Probab. 41 (2013) 1362–1426] on the limiting law of the latter one. Full Article
w A new McKean–Vlasov stochastic interpretation of the parabolic–parabolic Keller–Segel model: The one-dimensional case By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Denis Talay, Milica Tomašević. Source: Bernoulli, Volume 26, Number 2, 1323--1353.Abstract: In this paper, we analyze a stochastic interpretation of the one-dimensional parabolic–parabolic Keller–Segel system without cut-off. It involves an original type of McKean–Vlasov interaction kernel. At the particle level, each particle interacts with all the past of each other particle by means of a time integrated functional involving a singular kernel. At the mean-field level studied here, the McKean–Vlasov limit process interacts with all the past time marginals of its probability distribution in a similarly singular way. We prove that the parabolic–parabolic Keller–Segel system in the whole Euclidean space and the corresponding McKean–Vlasov stochastic differential equation are well-posed for any values of the parameters of the model. Full Article
w Strictly weak consensus in the uniform compass model on $mathbb{Z}$ By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Nina Gantert, Markus Heydenreich, Timo Hirscher. Source: Bernoulli, Volume 26, Number 2, 1269--1293.Abstract: We investigate a model for opinion dynamics, where individuals (modeled by vertices of a graph) hold certain abstract opinions. As time progresses, neighboring individuals interact with each other, and this interaction results in a realignment of opinions closer towards each other. This mechanism triggers formation of consensus among the individuals. Our main focus is on strong consensus (i.e., global agreement of all individuals) versus weak consensus (i.e., local agreement among neighbors). By extending a known model to a more general opinion space, which lacks a “central” opinion acting as a contraction point, we provide an example of an opinion formation process on the one-dimensional lattice $mathbb{Z}$ with weak consensus but no strong consensus. Full Article
w Consistent structure estimation of exponential-family random graph models with block structure By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Michael Schweinberger. Source: Bernoulli, Volume 26, Number 2, 1205--1233.Abstract: We consider the challenging problem of statistical inference for exponential-family random graph models based on a single observation of a random graph with complex dependence. To facilitate statistical inference, we consider random graphs with additional structure in the form of block structure. We have shown elsewhere that when the block structure is known, it facilitates consistency results for $M$-estimators of canonical and curved exponential-family random graph models with complex dependence, such as transitivity. In practice, the block structure is known in some applications (e.g., multilevel networks), but is unknown in others. When the block structure is unknown, the first and foremost question is whether it can be recovered with high probability based on a single observation of a random graph with complex dependence. The main consistency results of the paper show that it is possible to do so under weak dependence and smoothness conditions. These results confirm that exponential-family random graph models with block structure constitute a promising direction of statistical network analysis. Full Article
w Characterization of probability distribution convergence in Wasserstein distance by $L^{p}$-quantization error function By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Yating Liu, Gilles Pagès. Source: Bernoulli, Volume 26, Number 2, 1171--1204.Abstract: We establish conditions to characterize probability measures by their $L^{p}$-quantization error functions in both $mathbb{R}^{d}$ and Hilbert settings. This characterization is two-fold: static (identity of two distributions) and dynamic (convergence for the $L^{p}$-Wasserstein distance). We first propose a criterion on the quantization level $N$, valid for any norm on $mathbb{R}^{d}$ and any order $p$ based on a geometrical approach involving the Voronoï diagram. Then, we prove that in the $L^{2}$-case on a (separable) Hilbert space, the condition on the level $N$ can be reduced to $N=2$, which is optimal. More quantization based characterization cases in dimension 1 and a discussion of the completeness of a distance defined by the quantization error function can be found at the end of this paper. Full Article
w Interacting reinforced stochastic processes: Statistical inference based on the weighted empirical means By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Giacomo Aletti, Irene Crimaldi, Andrea Ghiglietti. Source: Bernoulli, Volume 26, Number 2, 1098--1138.Abstract: This work deals with a system of interacting reinforced stochastic processes , where each process $X^{j}=(X_{n,j})_{n}$ is located at a vertex $j$ of a finite weighted directed graph, and it can be interpreted as the sequence of “actions” adopted by an agent $j$ of the network. The interaction among the dynamics of these processes depends on the weighted adjacency matrix $W$ associated to the underlying graph: indeed, the probability that an agent $j$ chooses a certain action depends on its personal “inclination” $Z_{n,j}$ and on the inclinations $Z_{n,h}$, with $h eq j$, of the other agents according to the entries of $W$. The best known example of reinforced stochastic process is the Pólya urn. The present paper focuses on the weighted empirical means $N_{n,j}=sum_{k=1}^{n}q_{n,k}X_{k,j}$, since, for example, the current experience is more important than the past one in reinforced learning. Their almost sure synchronization and some central limit theorems in the sense of stable convergence are proven. The new approach with weighted means highlights the key points in proving some recent results for the personal inclinations $Z^{j}=(Z_{n,j})_{n}$ and for the empirical means $overline{X}^{j}=(sum_{k=1}^{n}X_{k,j}/n)_{n}$ given in recent papers (e.g. Aletti, Crimaldi and Ghiglietti (2019), Ann. Appl. Probab. 27 (2017) 3787–3844, Crimaldi et al. Stochastic Process. Appl. 129 (2019) 70–101). In fact, with a more sophisticated decomposition of the considered processes, we can understand how the different convergence rates of the involved stochastic processes combine. From an application point of view, we provide confidence intervals for the common limit inclination of the agents and a test statistics to make inference on the matrix $W$, based on the weighted empirical means. In particular, we answer a research question posed in Aletti, Crimaldi and Ghiglietti (2019). Full Article
w A unified principled framework for resampling based on pseudo-populations: Asymptotic theory By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Pier Luigi Conti, Daniela Marella, Fulvia Mecatti, Federico Andreis. Source: Bernoulli, Volume 26, Number 2, 1044--1069.Abstract: In this paper, a class of resampling techniques for finite populations under $pi $ps sampling design is introduced. The basic idea on which they rest is a two-step procedure consisting in: (i) constructing a “pseudo-population” on the basis of sample data; (ii) drawing a sample from the predicted population according to an appropriate resampling design. From a logical point of view, this approach is essentially based on the plug-in principle by Efron, at the “sampling design level”. Theoretical justifications based on large sample theory are provided. New approaches to construct pseudo populations based on various forms of calibrations are proposed. Finally, a simulation study is performed. Full Article
w Degeneracy in sparse ERGMs with functions of degrees as sufficient statistics By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Sumit Mukherjee. Source: Bernoulli, Volume 26, Number 2, 1016--1043.Abstract: A sufficient criterion for “non-degeneracy” is given for Exponential Random Graph Models on sparse graphs with sufficient statistics which are functions of the degree sequence. This criterion explains why statistics such as alternating $k$-star are non-degenerate, whereas subgraph counts are degenerate. It is further shown that this criterion is “almost” tight. Existence of consistent estimates is then proved for non-degenerate Exponential Random Graph Models. Full Article
w Recurrence of multidimensional persistent random walks. Fourier and series criteria By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST 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. Full Article
w Stochastic differential equations with a fractionally filtered delay: A semimartingale model for long-range dependent processes By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Richard A. Davis, Mikkel Slot Nielsen, Victor Rohde. Source: Bernoulli, Volume 26, Number 2, 799--827.Abstract: In this paper, we introduce a model, the stochastic fractional delay differential equation (SFDDE), which is based on the linear stochastic delay differential equation and produces stationary processes with hyperbolically decaying autocovariance functions. The model departs from the usual way of incorporating this type of long-range dependence into a short-memory model as it is obtained by applying a fractional filter to the drift term rather than to the noise term. The advantages of this approach are that the corresponding long-range dependent solutions are semimartingales and the local behavior of the sample paths is unaffected by the degree of long memory. We prove existence and uniqueness of solutions to the SFDDEs and study their spectral densities and autocovariance functions. Moreover, we define a subclass of SFDDEs which we study in detail and relate to the well-known fractionally integrated CARMA processes. Finally, we consider the task of simulating from the defining SFDDEs. Full Article
w Convergence and concentration of empirical measures under Wasserstein distance in unbounded functional spaces By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Jing Lei. Source: Bernoulli, Volume 26, Number 1, 767--798.Abstract: We provide upper bounds of the expected Wasserstein distance between a probability measure and its empirical version, generalizing recent results for finite dimensional Euclidean spaces and bounded functional spaces. Such a generalization can cover Euclidean spaces with large dimensionality, with the optimal dependence on the dimensionality. Our method also covers the important case of Gaussian processes in separable Hilbert spaces, with rate-optimal upper bounds for functional data distributions whose coordinates decay geometrically or polynomially. Moreover, our bounds of the expected value can be combined with mean-concentration results to yield improved exponential tail probability bounds for the Wasserstein error of empirical measures under Bernstein-type or log Sobolev-type conditions. Full Article
w A Feynman–Kac result via Markov BSDEs with generalised drivers By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Elena Issoglio, Francesco Russo. Source: Bernoulli, Volume 26, Number 1, 728--766.Abstract: In this paper, we investigate BSDEs where the driver contains a distributional term (in the sense of generalised functions) and derive general Feynman–Kac formulae related to these BSDEs. We introduce an integral operator to give sense to the equation and then we show the existence of a strong solution employing results on a related PDE. Due to the irregularity of the driver, the $Y$-component of a couple $(Y,Z)$ solving the BSDE is not necessarily a semimartingale but a weak Dirichlet process. Full Article
w Normal approximation for sums of weighted $U$-statistics – application to Kolmogorov bounds in random subgraph counting By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Nicolas Privault, Grzegorz Serafin. Source: Bernoulli, Volume 26, Number 1, 587--615.Abstract: We derive normal approximation bounds in the Kolmogorov distance for sums of discrete multiple integrals and weighted $U$-statistics made of independent Bernoulli random variables. Such bounds are applied to normal approximation for the renormalized subgraph counts in the Erdős–Rényi random graph. This approach completely solves a long-standing conjecture in the general setting of arbitrary graph counting, while recovering recent results obtained for triangles and improving other bounds in the Wasserstein distance. Full Article
w Consistent semiparametric estimators for recurrent event times models with application to virtual age models By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Eric Beutner, Laurent Bordes, Laurent Doyen. Source: Bernoulli, Volume 26, Number 1, 557--586.Abstract: Virtual age models are very useful to analyse recurrent events. Among the strengths of these models is their ability to account for treatment (or intervention) effects after an event occurrence. Despite their flexibility for modeling recurrent events, the number of applications is limited. This seems to be a result of the fact that in the semiparametric setting all the existing results assume the virtual age function that describes the treatment (or intervention) effects to be known. This shortcoming can be overcome by considering semiparametric virtual age models with parametrically specified virtual age functions. Yet, fitting such a model is a difficult task. Indeed, it has recently been shown that for these models the standard profile likelihood method fails to lead to consistent estimators. Here we show that consistent estimators can be constructed by smoothing the profile log-likelihood function appropriately. We show that our general result can be applied to most of the relevant virtual age models of the literature. Our approach shows that empirical process techniques may be a worthwhile alternative to martingale methods for studying asymptotic properties of these inference methods. A simulation study is provided to illustrate our consistency results together with an application to real data. Full Article
w High dimensional deformed rectangular matrices with applications in matrix denoising By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Xiucai Ding. Source: Bernoulli, Volume 26, Number 1, 387--417.Abstract: We consider the recovery of a low rank $M imes N$ matrix $S$ from its noisy observation $ ilde{S}$ in the high dimensional framework when $M$ is comparable to $N$. We propose two efficient estimators for $S$ under two different regimes. Our analysis relies on the local asymptotics of the eigenstructure of large dimensional rectangular matrices with finite rank perturbation. We derive the convergent limits and rates for the singular values and vectors for such matrices. Full Article
w SPDEs with fractional noise in space: Continuity in law with respect to the Hurst index By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Luca M. Giordano, Maria Jolis, Lluís Quer-Sardanyons. Source: Bernoulli, Volume 26, Number 1, 352--386.Abstract: In this article, we consider the quasi-linear stochastic wave and heat equations on the real line and with an additive Gaussian noise which is white in time and behaves in space like a fractional Brownian motion with Hurst index $Hin (0,1)$. The drift term is assumed to be globally Lipschitz. We prove that the solution of each of the above equations is continuous in terms of the index $H$, with respect to the convergence in law in the space of continuous functions. Full Article
w Weak convergence of quantile and expectile processes under general assumptions By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Tobias Zwingmann, Hajo Holzmann. Source: Bernoulli, Volume 26, Number 1, 323--351.Abstract: We show weak convergence of quantile and expectile processes to Gaussian limit processes in the space of bounded functions endowed with an appropriate semimetric which is based on the concepts of epi- and hypo- convergence as introduced in A. Bücher, J. Segers and S. Volgushev (2014), ‘ When Uniform Weak Convergence Fails: Empirical Processes for Dependence Functions and Residuals via Epi- and Hypographs ’, Annals of Statistics 42 . We impose assumptions for which it is known that weak convergence with respect to the supremum norm generally fails to hold. For quantiles, we consider stationary observations, where the marginal distribution function is assumed to be strictly increasing and continuous except for finitely many points and to admit strictly positive – possibly infinite – left- and right-sided derivatives. For expectiles, we focus on independent and identically distributed (i.i.d.) observations. Only a finite second moment and continuity at the boundary points but no further smoothness properties of the distribution function are required. We also show consistency of the bootstrap for this mode of convergence in the i.i.d. case for quantiles and expectiles. Full Article
w Needles and straw in a haystack: Robust confidence for possibly sparse sequences By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST 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. Full Article
w A new method for obtaining sharp compound Poisson approximation error estimates for sums of locally dependent random variables By projecteuclid.org Published On :: Thu, 05 Aug 2010 15:41 EDT Michael V. Boutsikas, Eutichia VaggelatouSource: Bernoulli, Volume 16, Number 2, 301--330.Abstract: Let X 1 , X 2 , …, X n be a sequence of independent or locally dependent random variables taking values in ℤ + . In this paper, we derive sharp bounds, via a new probabilistic method, for the total variation distance between the distribution of the sum ∑ i =1 n X i and an appropriate Poisson or compound Poisson distribution. These bounds include a factor which depends on the smoothness of the approximating Poisson or compound Poisson distribution. This “smoothness factor” is of order O( σ −2 ), according to a heuristic argument, where σ 2 denotes the variance of the approximating distribution. In this way, we offer sharp error estimates for a large range of values of the parameters. Finally, specific examples concerning appearances of rare runs in sequences of Bernoulli trials are presented by way of illustration. Full Article
w The Thomson family : fisherman in Buckhaven, retailers in Kapunda / compiled by Elizabeth Anne Howell. By www.catalog.slsa.sa.gov.au Published On :: Thomson (Family) Full Article
w My dear sir / Gwen Waters. By www.catalog.slsa.sa.gov.au Published On :: Braddock, William, 1798-1869 -- Correspondence. Full Article
w The Mercer story and Amy's story / by Amy Moore ; with Ray Moore. By www.catalog.slsa.sa.gov.au Published On :: Moore, Amy, 1908-2005. Full Article
w The Barnes story / by Amy Moore ; with Ray Moore. By www.catalog.slsa.sa.gov.au Published On :: Moore, Amy, 1908-2005 -- Family. Full Article
w Newsletter (South East Family History Group (S.A.)). By www.catalog.slsa.sa.gov.au Published On :: South East Family History Group (S.A.) -- Periodicals. Full Article
w From Westphalia to South Australia : the story of Franz Heinrich Ernst Siekmann / by Peter Brinkworth. By www.catalog.slsa.sa.gov.au Published On :: Siekmann, Francis Heinrich Ernst, 1830-1917. Full Article
w 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. By www.catalog.slsa.sa.gov.au Published On :: Hewish Henry -- Family. Full Article
w With a bottle of whisky in my hand : the family of James Grant and Isabella Masson / by Carolyn Cowgill. By www.catalog.slsa.sa.gov.au Published On :: Grant (Family) Full Article
w The Yangya Hicks : tales from the Hicks family of Yangya near Gladstone, South Australia, written from the 12th of May 1998 / by Joyce Coralie Hale (nee Hicks) (28.12.1923-17.12.2003). By www.catalog.slsa.sa.gov.au Published On :: Hicks (Family) Full Article
w List of family history books owned by Roy Klemm. By www.catalog.slsa.sa.gov.au Published On :: Family histories -- South Australia -- Bibliography. Full Article
w Discover Protestant nonconformity in England and Wales / Paul Blake. By www.catalog.slsa.sa.gov.au Published On :: Dissenters, Religious -- Great Britain. Full Article
w Welsh given names : popularity, spelling variants, diminutives and abbreviations / by Carol Baxter. By www.catalog.slsa.sa.gov.au Published On :: Names, Personal -- Welsh. Full Article
w Our Lady of Grace family page of history : a bookweek bicentennial project / edited by Janeen Brian. By www.catalog.slsa.sa.gov.au Published On :: Our Lady of Grace School (Glengowrie, S.A.) Full Article
w Daws : the ancestors of Revell Daws. By www.catalog.slsa.sa.gov.au Published On :: Daws, Revell. Full Article
w South Australian history sources / by Andrew Guy Peake. By www.catalog.slsa.sa.gov.au Published On :: South Australia -- History -- Sources. Full Article
w Traegers in Australia. 3, Ernst's story : the story of Ernst Wilhelm Traeger and Johanne Dorothea nee Lissmann, and their descendants, 1856-2018. By www.catalog.slsa.sa.gov.au Published On :: Traeger, Ernst Wilhelm, 1805-1874. Full Article
w Living through English history : stories of the Urlwin, Brittridge, Vasper, Partridge and Ellerby families / Janet McLeod. By www.catalog.slsa.sa.gov.au Published On :: Urlwin (Family). Full Article
w Slow tain to Auschwitz : memoirs of a life in war and peace / Peter Kraus. By www.catalog.slsa.sa.gov.au Published On :: Kraus, Peter -- Biography. Full Article
w From Wends we came : the story of Johann and Maria Huppatz & their descendants / compiled by Frank Huppatz and Rone McDonnell. By www.catalog.slsa.sa.gov.au Published On :: Huppatz (Family). Full Article