1 code implementation • 19 Apr 2024 • Tong Xu, Armeen Taeb, Simge Küçükyavuz, Ali Shojaie
We study the problem of learning directed acyclic graphs from continuous observational data, generated according to a linear Gaussian structural equation model.
no code implementations • 24 Mar 2024 • Ali Shojaie, Wenyu Chen
In general, learning the DAG structure is both computationally and statistically challenging.
no code implementations • 11 Jun 2023 • Si Cheng, Jon Wakefield, Ali Shojaie
Doubly-stochastic point processes model the occurrence of events over a spatial domain as an inhomogeneous Poisson process conditioned on the realization of a random intensity function.
no code implementations • 14 Oct 2022 • Xiudi Li, Abolfazl Safikhani, Ali Shojaie
To overcome these challenges, in this paper we propose an approximate EM algorithm for Markov-switching VAR models that leads to efficient computation and also facilitates the investigation of asymptotic properties of the resulting parameter estimates.
1 code implementation • 23 Sep 2021 • Xu Wang, Ali Shojaie
Modern high-dimensional point process data, especially those from neuroscience experiments, often involve observations from multiple conditions and/or experiments.
no code implementations • 22 Sep 2021 • Xu Wang, Ali Shojaie
Thanks to technological advances leading to near-continuous time observations, emerging multivariate point process data offer new opportunities for causal discovery.
no code implementations • 10 Sep 2021 • Shiqing Yu, Mathias Drton, Ali Shojaie
Applications such as the analysis of microbiome data have led to renewed interest in statistical methods for compositional data, i. e., multivariate data in the form of probability vectors that contain relative proportions.
1 code implementation • 20 May 2021 • Wenyu Chen, Mathias Drton, Ali Shojaie
Ancestral relations between variables play an important role in causal modeling.
no code implementations • 5 May 2021 • Ali Shojaie, Emily B. Fox
Introduced more than a half century ago, Granger causality has become a popular tool for analyzing time series data in many application domains, from economics and finance to genomics and neuroscience.
no code implementations • 5 May 2021 • Yunhua Xiang, Tianyu Zhang, Xu Wang, Ali Shojaie, Noah Simon
Originally developed for imputing missing entries in low rank, or approximately low rank matrices, matrix completion has proven widely effective in many problems where there is no reason to assume low-dimensional linear structure in the underlying matrix, as would be imposed by rank constraints.
no code implementations • 24 Sep 2020 • Shiqing Yu, Mathias Drton, Ali Shojaie
Score matching provides a powerful tool for estimating densities with such intractable normalizing constants, but as originally proposed is limited to densities on $\mathbb{R}^m$ and $\mathbb{R}_+^m$.
1 code implementation • 15 Jul 2020 • Xu Wang, Mladen Kolar, Ali Shojaie
The key ingredient for this inference procedure is a new concentration inequality on the first- and second-order statistics for integrated stochastic processes, which summarize the entire history of the process.
no code implementations • 29 May 2020 • Simge Kucukyavuz, Ali Shojaie, Hasan Manzour, Linchuan Wei, Hao-Hsiang Wu
The optimal solution to this mathematical program is known to have desirable statistical properties under certain conditions.
no code implementations • 9 Mar 2020 • Ali Shojaie
Networks effectively capture interactions among components of complex systems, and have thus become a mainstay in many scientific disciplines.
1 code implementation • 16 Dec 2019 • Lina Lin, Mathias Drton, Ali Shojaie
Our framework is inspired by a recent line of work that proposes de-biasing penalized estimators to perform inference for high-dimensional linear models with fixed effects only.
no code implementations • 23 Apr 2019 • Hasan Manzour, Simge Küçükyavuz, Ali Shojaie
In this paper, we study the problem of learning an optimal DAG from continuous observational data.
no code implementations • 11 Mar 2019 • Asad Haris, Noah Simon, Ali Shojaie
We present a unified framework for estimation and analysis of generalized additive models in high dimensions.
no code implementations • NeurIPS 2018 • Asad Haris, Noah Simon, Ali Shojaie
We prove minimax optimal convergence rates under a weak compatibility condition for sparse additive models.
no code implementations • 26 Dec 2018 • Shiqing Yu, Mathias Drton, Ali Shojaie
The score matching method of Hyv\"arinen [2005] avoids direct calculation of the normalizing constant and yields closed-form estimates for exponential families of continuous distributions over $\mathbb{R}^m$.
no code implementations • 16 Jun 2018 • Arjun Sondhi, Ali Shojaie
In particular, it results in more efficient and accurate estimation in large networks containing hub nodes, which are common in biological systems.
3 code implementations • 16 Feb 2018 • Alex Tank, Ian Covert, Nicholas Foti, Ali Shojaie, Emily Fox
We show that our neural Granger causality methods outperform state-of-the-art nonlinear Granger causality methods on the DREAM3 challenge data.
no code implementations • 22 Nov 2017 • Alex Tank, Emily B. Fox, Ali Shojaie
We present an efficient alternating direction method of multipliers (ADMM) algorithm for segmenting a multivariate non-stationary time series with structural breaks into stationary regions.
1 code implementation • 22 Nov 2017 • Alex Tank, Ian Cover, Nicholas J. Foti, Ali Shojaie, Emily B. Fox
A sufficient condition for Granger non-causality in this setting is that all of the outgoing weights of the input data, the past lags of a series, to the first hidden layer are zero.
no code implementations • 16 May 2017 • Sen Zhao, Daniela Witten, Ali Shojaie
In this paper, we consider a simple and very na\"{i}ve two-step procedure for this task, in which we (i) fit a lasso model in order to obtain a subset of the variables, and (ii) fit a least squares model on the lasso-selected set.
no code implementations • 30 Nov 2016 • Asad Haris, Ali Shojaie, Noah Simon
We further establish minimax rates for a large class of sparse additive models.
no code implementations • 2 Jan 2016 • Takumi Saegusa, Ali Shojaie
Further, to extend the applicability of the method to the settings with unknown populations structure, we propose a Laplacian penalty based on hierarchical clustering, and discuss conditions under which this data-driven choice results in consistent estimation of precision matrices in heterogenous populations.
no code implementations • 12 Jan 2014 • Arend Voorman, Ali Shojaie, Daniela Witten
Further, when an $\ell_2$ penalty is used, the test corresponds precisely to a score test in a mixed effects model, in which the effects of all but one feature are assumed to be random.
no code implementations • 2 Dec 2013 • Ali Shojaie, Alexandra Jauhiainen, Michael Kallitsis, George Michailidis
The proposed approach is based on a three-step algorithm to estimate the underlying directed but cyclic network, that uses as input both perturbation screens and steady state gene expression data.
no code implementations • 19 Jul 2013 • Kean Ming Tan, Daniela Witten, Ali Shojaie
We begin by introducing a surprising connection between the graphical lasso and hierarchical clustering: the graphical lasso in effect performs a two-step procedure, in which (1) single linkage hierarchical clustering is performed on the variables in order to identify connected components, and then (2) an l1-penalized log likelihood is maximized on the subset of variables within each connected component.
no code implementations • NeurIPS 2010 • Ali Shojaie, George Michailidis
Network models are widely used to capture interactions among component of complex systems, such as social and biological.