Search results for "lasso"
showing 10 items of 110 documents
The Induced Smoothed lasso: A practical framework for hypothesis testing in high dimensional regression.
2020
This paper focuses on hypothesis testing in lasso regression, when one is interested in judging statistical significance for the regression coefficients in the regression equation involving a lot of covariates. To get reliable p-values, we propose a new lasso-type estimator relying on the idea of induced smoothing which allows to obtain appropriate covariance matrix and Wald statistic relatively easily. Some simulation experiments reveal that our approach exhibits good performance when contrasted with the recent inferential tools in the lasso framework. Two real data analyses are presented to illustrate the proposed framework in practice.
cglasso: An R Package for Conditional Graphical Lasso Inference with Censored and Missing Values
2023
Sparse graphical models have revolutionized multivariate inference. With the advent of high-dimensional multivariate data in many applied fields, these methods are able to detect a much lower-dimensional structure, often represented via a sparse conditional independence graph. There have been numerous extensions of such methods in the past decade. Many practical applications have additional covariates or suffer from missing or censored data. Despite the development of these extensions of sparse inference methods for graphical models, there have been so far no implementations for, e.g., conditional graphical models. Here we present the general-purpose package cglasso for estimating sparse co…
On the sign recovery by LASSO, thresholded LASSO and thresholded Basis Pursuit Denoising
2020
Basis Pursuit (BP), Basis Pursuit DeNoising (BPDN), and LASSO are popular methods for identifyingimportant predictors in the high-dimensional linear regression model Y = Xβ + ε. By definition, whenε = 0, BP uniquely recovers β when Xβ = Xb and β different than b implies L1 norm of β is smaller than the L1 norm of b (identifiability condition). Furthermore, LASSO can recover the sign of β only under a much stronger irrepresentability condition. Meanwhile, it is known that the model selection properties of LASSO can be improved by hard-thresholdingits estimates. This article supports these findings by proving that thresholded LASSO, thresholded BPDNand thresholded BP recover the sign of β in …
Latest Cretaceous storm-generated sea grass accumulations in the Maastrichtian type area, the Netherlands – preliminary observations
2019
Abstract Ever since the first description of fossil material during the mid-nineteenth century, sea grass has been shown to be quite commonly preserved in ‘pockets’ or ‘clumps’ at certain levels within the Gulpen, Maastricht and Kunrade formations in southern Limburg (the Netherlands) and contiguous areas in northeast Belgium. In those places where silicification occurred during early diagenesis, even completely silicified and three-dimensionally preserved stems and roots can be found, mostly of Thalassocharis bosquetii, in association with fully marine molluscs such as dentaliid scaphopods and a range of larger foraminifera, bivalves, gastropods and ammonites. Such occurrences are best kno…
Supervised Analysis for Phenotype Identification: The Case of Heart Failure Ejection Fraction Class
2021
Artificial Intelligence is creating a paradigm shift in health care, with phenotyping patients through clustering techniques being one of the areas of interest. Objective: To develop a predictive model to classify heart failure (HF) patients according to their left ventricular ejection fraction (LVEF), by using available data from Electronic Health Records (EHR). Subjects and methods: 2854 subjects over 25 years old with a diagnosis of HF and LVEF, measured by echocardiography, were selected to develop an algorithm to predict patients with reduced EF using supervised analysis. The performance of the developed algorithm was tested in heart failure patients from Primary Care. To select the mo…
Observaciones, sobre un tratado, que escrivio ... Fr. Diego Tello, con el titulo de Suffragio a la piedad, con que la Nacion Española desea, y solic…
1750
Sig. A-S2 Escut xil. dels mercedaris al final Reclams. - Cristus
Variable selection with unbiased estimation: the CDF penalty
2022
We propose a new SCAD-type penalty in general regression models. The new penalty can be considered a competitor of the LASSO, SCAD or MCP penalties, as it guarantees sparse variable selection, i.e., null regression coefficient estimates, while attenuating bias for the non-null estimates. In this work, the method is discussed, and some comparisons are presented.
Variable Selection with Quasi-Unbiased Estimation: the CDF Penalty
2022
We propose a new non-convex penalty in linear regression models. The new penalty function can be considered a competitor of the LASSO, SCAD or MCP penalties, as it guarantees sparse variable selection while reducing bias for the non-null estimates. We introduce the methodology and present some comparisons among different approaches.
Vix: The Temptation of the City
2019
International audience; Ancient and modern geographers tend to use three criteria to define cities: a population above 5,000 inhabitants, the presence of a variety of activities, and a network connecting them with other establishments. Plato, Herodotus, Pausanias, and many others had preceded them in attempting to establish a paradigm for the city or polis. The Celtic princely seat on Vix-Mont Lassois is considered a coherent and organised entity, consisting of a quasi-urban space. At Vix, the latest investigations (2016‑2019) have revealed remains that suggest the possibility of harbour installations on the banks of the Seine. The notion of urbanisation or proto-urbanisation has been put f…
Das Bleigewicht aus dem Hofareal der Fürstin von Vix
2021
International audience; The Lead Weight from the Courtyard of the Lady of VixThe Mont Lassois near Vix, Dép. Côte d’Or, as well as the Heuneburg, counts as one of the best researched princelyseats in the early Celtic western Hallstatt zone. In 1953 the late Hallstatt grave of Vix was discovered. The old excavations(1930-1974) have been reactivated by the German-French research project »Celtic Princely Seats West of theRhine« (1991-1997) and the French PCR-project (Projet collectif de recherche) »Vix and its Environment« (since 2002)with the participation of the universities of Dijon, Kiel, Vienna and Zurich. During the investigation of the late Hallstattcourtyard of the Lady of Vix on the h…