Search Results for author: Ali Shojaie

Found 30 papers, 7 papers with code

Integer Programming for Learning Directed Acyclic Graphs from Non-identifiable Gaussian Models

1 code implementation19 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.

Learning Directed Acyclic Graphs from Partial Orderings

no code implementations24 Mar 2024 Ali Shojaie, Wenyu Chen

In general, learning the DAG structure is both computationally and statistically challenging.

A Penalized Poisson Likelihood Approach to High-Dimensional Semi-Parametric Inference for Doubly-Stochastic Point Processes

no code implementations11 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.

Point Processes

Estimation of High-Dimensional Markov-Switching VAR Models with an Approximate EM Algorithm

no code implementations14 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.

Time Series Time Series Analysis

Joint Estimation and Inference for Multi-Experiment Networks of High-Dimensional Point Processes

1 code implementation23 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.

Point Processes

Causal Discovery in High-Dimensional Point Process Networks with Hidden Nodes

no code implementations22 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.

Causal Discovery Vocal Bursts Intensity Prediction

Interaction Models and Generalized Score Matching for Compositional Data

no code implementations10 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.

Definite Non-Ancestral Relations and Structure Learning

1 code implementation20 May 2021 Wenyu Chen, Mathias Drton, Ali Shojaie

Ancestral relations between variables play an important role in causal modeling.

Granger Causality: A Review and Recent Advances

no code implementations5 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.

Time Series Time Series Analysis

On the Optimality of Nuclear-norm-based Matrix Completion for Problems with Smooth Non-linear Structure

no code implementations5 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.

Matrix Completion

Generalized Score Matching for General Domains

no code implementations24 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 $\mathbb{R}_+^m$.

Statistical Inference for Networks of High-Dimensional Point Processes

1 code implementation15 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.

Point Processes Vocal Bursts Intensity Prediction

Consistent Second-Order Conic Integer Programming for Learning Bayesian Networks

no code implementations29 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.

Differential Network Analysis: A Statistical Perspective

no code implementations9 Mar 2020 Ali Shojaie

Networks effectively capture interactions among components of complex systems, and have thus become a mainstay in many scientific disciplines.

BIG-bench Machine Learning

Statistical significance in high-dimensional linear mixed models

1 code implementation16 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.

valid Vocal Bursts Intensity Prediction

Integer Programming for Learning Directed Acyclic Graphs from Continuous Data

no code implementations23 Apr 2019 Hasan Manzour, Simge Küçükyavuz, Ali Shojaie

In this paper, we study the problem of learning an optimal DAG from continuous observational data.

Generalized Sparse Additive Models

no code implementations11 Mar 2019 Asad Haris, Noah Simon, Ali Shojaie

We present a unified framework for estimation and analysis of generalized additive models in high dimensions.

Additive models

Wavelet regression and additive models for irregularly spaced data

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.

Additive models regression

Generalized Score Matching for Non-Negative Data

no code implementations26 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 $\mathbb{R}^m$.

Numerical Integration

The Reduced PC-Algorithm: Improved Causal Structure Learning in Large Random Networks

no code implementations16 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.

Neural Granger Causality

3 code implementations16 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.

Time Series Analysis

An Efficient ADMM Algorithm for Structural Break Detection in Multivariate Time Series

no code implementations22 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.

Time Series Time Series Analysis

An Interpretable and Sparse Neural Network Model for Nonlinear Granger Causality Discovery

1 code implementation22 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.

Time Series Time Series Analysis

In Defense of the Indefensible: A Very Naive Approach to High-Dimensional Inference

no code implementations16 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.

regression valid

Joint Estimation of Precision Matrices in Heterogeneous Populations

no code implementations2 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.

Clustering Variable Selection

Inference in High Dimensions with the Penalized Score Test

no code implementations12 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.

regression Variable Selection +1

Inferring Regulatory Networks by Combining Perturbation Screens and Steady State Gene Expression Profiles

no code implementations2 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.

The Cluster Graphical Lasso for improved estimation of Gaussian graphical models

no code implementations19 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.

Clustering Model Selection

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