{"title":"An exponential inequality for Hilbert-valued U-statistics of i.i.d. data","authors":"Davide Giraudo","doi":"10.1016/j.jmva.2025.105406","DOIUrl":"10.1016/j.jmva.2025.105406","url":null,"abstract":"<div><div>In this paper, we establish an exponential inequality for <span><math><mi>U</mi></math></span>-statistics of i.i.d. data, varying kernel and taking values in a separable Hilbert space. The bound is expressed as a sum of an exponential term plus an other one involving the tail of a sum of squared norms. We start by the degenerate case. Then we provide applications to <span><math><mi>U</mi></math></span>-statistics of not necessarily degenerate fixed kernel, incomplete <span><math><mi>U</mi></math></span>-statistics and weighted <span><math><mi>U</mi></math></span>-statistics.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105406"},"PeriodicalIF":1.4,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fisher’s legacy of directional statistics, and beyond to statistics on manifolds","authors":"Kanti V. Mardia","doi":"10.1016/j.jmva.2024.105404","DOIUrl":"10.1016/j.jmva.2024.105404","url":null,"abstract":"<div><div>It is not an exaggeration to say that R.A. Fisher is the Albert Einstein of Statistics. He pioneered almost all the main branches of statistics, but it is not as well known that he opened the area of Directional Statistics with his 1953 paper introducing a distribution on the sphere which is now known as the Fisher distribution. He stressed that for spherical data one should take into account that the data is on a manifold. We will describe this Fisher distribution and reanalyze his geological data. We also comment on the two goals he set himself in that paper, and on how he reinvented the von Mises distribution on the circle. Since then, many extensions of this distribution have appeared bearing Fisher’s name such as the von Mises–Fisher distribution and the matrix Fisher distribution. In fact, the subject of Directional Statistics has grown tremendously in the last two decades with new applications emerging in life sciences, image analysis, machine learning and so on. We give a recent new method of constructing the Fisher type distributions on manifolds which has been motivated by some problems in machine learning. The number of directional distributions has increased since then, including the bivariate von Mises distribution and we describe its connection to work resulting in the 2024 Nobel-winning AlphaFold (in Chemistry). Further, the subject has evolved as Statistics on Manifolds which also includes the new field of Shape Analysis, and finally, we end with a historical note pointing out some correspondence between D’Arcy Thompson and R.A. Fisher related to Shape Analysis.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105404"},"PeriodicalIF":1.4,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SFQRA: Scaled factor-augmented quantile regression with aggregation in conditional mean forecasting","authors":"Lei Shu , Yifan Hao , Yu Chen , Qing Yang","doi":"10.1016/j.jmva.2024.105405","DOIUrl":"10.1016/j.jmva.2024.105405","url":null,"abstract":"<div><div>Achieving robust forecasts for a single time series with many covariates and possible nonlinear effects is a problem worth investigating. In this paper, a scaled factor-augmented quantile regression with aggregation (SFQRA) method is proposed for an effective prediction. It first estimates different conditional quantiles by introducing scaled covariates to the factor-augmented quantile regression, which not only combats the curse of dimensionality but also includes the target information in the estimation. Then the different conditional quantiles are aggregated appropriately to a robust forecast. Moreover, combining SFQRA with feature screening via an aggregated quantile correlation allows it to be extended to handle cases when only a portion of covariates is informative. The effectiveness of the proposed methods is justified theoretically, under the framework of large cross-sections and large time dimensions while no restriction is imposed on the relation between them. Various simulation studies and real data analyses demonstrate the superiority of the newly proposed method in forecasting.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105405"},"PeriodicalIF":1.4,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Semi-functional varying coefficient mode-based regression","authors":"Tao Wang","doi":"10.1016/j.jmva.2024.105402","DOIUrl":"10.1016/j.jmva.2024.105402","url":null,"abstract":"<div><div>We propose estimating semi-functional varying coefficient regression based on the mode value through a kernel objective function, where the bandwidth included is treated as a tuning parameter to achieve efficiency and robustness. For estimation, functional principal component basis functions are utilized to approximate the slope function and functional predictor variable, while B-spline functions are employed to approximate the varying coefficient component. Under mild regularity conditions, the convergence rates of the resulting estimators for the unknown slope function and varying coefficient are established under various cases. To numerically estimate the proposed model, we recommend employing a computationally efficient mode expectation–maximization algorithm with the aid of a Gaussian kernel. The tuning parameters are selected using the mode-based Bayesian information criterion and cross-validation procedures. Built upon the generalized likelihood technique, we further develop a goodness-of-fit test to assess the constancy of varying coefficient functions and put forward a wild bootstrap procedure for estimating the corresponding critical values. The finite sample performance of the developed estimators is illustrated through Monte Carlo simulations and real data analysis related to the Tecator data. The results produced by the propounded method are compared favorably with those obtained from alternative estimation techniques.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105402"},"PeriodicalIF":1.4,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Yanpeng , Xie Jiahui , Zhou Guoliang , Zhou Wang
{"title":"Sequential estimation of high-dimensional signal plus noise models under general elliptical frameworks","authors":"Li Yanpeng , Xie Jiahui , Zhou Guoliang , Zhou Wang","doi":"10.1016/j.jmva.2024.105403","DOIUrl":"10.1016/j.jmva.2024.105403","url":null,"abstract":"<div><div>High dimensional data analysis has attracted considerable interest and is facing new challenges, one of which is the increasingly available data with noise corrupted and in a streaming manner, such as signals and stocks. In this paper, we develop a sequential method to dynamically update the estimates of signal and noise strength in signal plus noise models. The proposed sequential method is easy to compute based on the stored statistics and the current data point. The consistency and, more importantly, the asymptotic normality of the estimators of signal strength and noise level are demonstrated for high dimensional settings under mild conditions. Simulations and real data examples are further provided to illustrate the practical utility of our proposal.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105403"},"PeriodicalIF":1.4,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the consistency of the jackknife estimator of the asymptotic variance of spatial median","authors":"František Rublík","doi":"10.1016/j.jmva.2024.105399","DOIUrl":"10.1016/j.jmva.2024.105399","url":null,"abstract":"<div><div>It is shown that the usual delete-1 jackknife variance estimator of the asymptotic variance of spatial median is consistent. This is proved under the assumptions that the dimension of the data <span><math><mrow><mi>d</mi><mo>≥</mo><mn>3</mn></mrow></math></span>, the sampled distribution possesses a density with respect to the Lebesgue measure and this density is bounded on every bounded subset of <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span>.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105399"},"PeriodicalIF":1.4,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-dimensional projection-based ANOVA test","authors":"Weihao Yu , Qi Zhang , Weiyu Li","doi":"10.1016/j.jmva.2024.105401","DOIUrl":"10.1016/j.jmva.2024.105401","url":null,"abstract":"<div><div>In bioinformation and medicine, an enormous amount of high-dimensional multi-population data is collected. For the inference of several-samples mean problem, traditional tests do not perform well and many new theories mainly focus on normal distribution and low correlation assumptions. Motivated by the weighted sign test, we propose two projection-based tests which are robust against the choice of correlation matrix. One test utilizes Scheffe’s transformation to generate a group of new samples and derives the optimal projection direction. The other test is adaptive to projection direction and is generalized to the assumption of the whole elliptical distribution and independent component model. Further the theoretical properties are deduced and numerical experiments are carried out to examine the finite sample performance. They show that our tests outperform others under certain circumstances.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105401"},"PeriodicalIF":1.4,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quadratic inference with dense functional responses","authors":"Pratim Guha Niyogi , Ping-Shou Zhong","doi":"10.1016/j.jmva.2024.105400","DOIUrl":"10.1016/j.jmva.2024.105400","url":null,"abstract":"<div><div>We address the challenge of estimation in the context of constant linear effect models with dense functional responses. In this framework, the conditional expectation of the response curve is represented by a linear combination of functional covariates with constant regression parameters. In this paper, we present an alternative solution by employing the quadratic inference approach, a well-established method for analyzing correlated data, to estimate the regression coefficients. Our approach leverages non-parametrically estimated basis functions, eliminating the need for choosing working correlation structures. Furthermore, we demonstrate that our method achieves a parametric <span><math><msqrt><mrow><mi>n</mi></mrow></msqrt></math></span>-convergence rate, contingent on an appropriate choice of bandwidth. This convergence is observed when the number of repeated measurements per trajectory exceeds a certain threshold, specifically, when it surpasses <span><math><msup><mrow><mi>n</mi></mrow><mrow><msub><mrow><mi>a</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></msup></math></span>, with <span><math><mi>n</mi></math></span> representing the number of trajectories. Additionally, we establish the asymptotic normality of the resulting estimator. The performance of the proposed method is compared with that of existing methods through extensive simulation studies, where our proposed method outperforms. Real data analysis is also conducted to demonstrate the proposed method.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"207 ","pages":"Article 105400"},"PeriodicalIF":1.4,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143134411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alain Desgagné , Christian Genest , Frédéric Ouimet
{"title":"Asymptotics for non-degenerate multivariate U-statistics with estimated nuisance parameters under the null and local alternative hypotheses","authors":"Alain Desgagné , Christian Genest , Frédéric Ouimet","doi":"10.1016/j.jmva.2024.105398","DOIUrl":"10.1016/j.jmva.2024.105398","url":null,"abstract":"<div><div>The large-sample behavior of non-degenerate multivariate <span><math><mi>U</mi></math></span>-statistics of arbitrary degree is investigated under the assumption that their kernel depends on parameters that can be estimated consistently. Mild regularity conditions are provided which guarantee that once properly normalized, such statistics are asymptotically multivariate Gaussian both under the null hypothesis and sequences of local alternatives. The work of Randles (1982, <em>Ann. Statist.</em>) is extended in three ways: the data and the kernel values can be multivariate rather than univariate, the limiting behavior under local alternatives is studied for the first time, and the effect of knowing some of the nuisance parameters is quantified. These results can be applied to a broad range of goodness-of-fit testing contexts, as shown in two specific examples.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"208 ","pages":"Article 105398"},"PeriodicalIF":1.4,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexandra Soberon , Massimiliano Mazzanti , Antonio Musolesi , Juan M. Rodriguez-Poo
{"title":"Efficient estimation of a partially linear panel data model with cross-sectional dependence","authors":"Alexandra Soberon , Massimiliano Mazzanti , Antonio Musolesi , Juan M. Rodriguez-Poo","doi":"10.1016/j.jmva.2024.105393","DOIUrl":"10.1016/j.jmva.2024.105393","url":null,"abstract":"<div><div>This paper considers efficiency improvements in a partially linear panel data model that accounts for possible nonlinear effects of common covariates and allows for cross-sectional dependence arising simultaneously from unobserved common factors and spatial dependence. A generalized least squares-type estimator is proposed by taking into account this dependence structure. Also, possible gains in terms of the rate of convergence are studied. A Monte Carlo study is carried out to investigate the proposed estimators’ finite sample performance. Further, an empirical application is conducted to assess the impact of the carbon price linked to the European Union Emission Trading System on carbon dioxide emissions.</div></div>","PeriodicalId":16431,"journal":{"name":"Journal of Multivariate Analysis","volume":"206 ","pages":"Article 105393"},"PeriodicalIF":1.4,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143137999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}