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Sampled network data are widely used in empirical research because collecting complete network information is costly. However, empirical analyses based on sampled networks may lead to biased estimators. We propose a nonparametric imputation…

Econometrics · Economics 2026-05-12 Ge Sun , Weisheng Zhang

Irregularly sampled time series (ISTS), characterized by non-uniform time intervals with natural missingness, are prevalent in real-world applications. Existing approaches for ISTS modeling primarily rely on observed values to impute…

Machine Learning · Computer Science 2025-11-18 Jiexi Liu , Meng Cao , Songcan Chen

Multivariate time series (MTS) data, when sampled irregularly and asynchronously, often present extensive missing values. Conventional methodologies for MTS analysis tend to rely on temporal embeddings based on timestamps that necessitate…

Machine Learning · Computer Science 2024-05-28 Chun-Kai Huang , Yi-Hsien Hsieh , Ta-Jung Chien , Li-Cheng Chien , Shao-Hua Sun , Tung-Hung Su , Jia-Horng Kao , Che Lin

Irregular Time Series Data (IRTS) has shown increasing prevalence in real-world applications. We observed that IRTS can be divided into two specialized types: Natural Irregular Time Series (NIRTS) and Accidental Irregular Time Series…

Machine Learning · Computer Science 2024-10-17 Liangwei Nathan Zheng , Zhengyang Li , Chang George Dong , Wei Emma Zhang , Lin Yue , Miao Xu , Olaf Maennel , Weitong Chen

Human activity recognition (HAR) ideally relies on data from wearable or environment-instrumented sensors sampled at regular intervals, enabling standard neural network models optimized for consistent time-series data as input. However,…

Signal Processing · Electrical Eng. & Systems 2025-01-28 Mengxi Liu , Daniel Geißler , Sizhen Bian , Bo Zhou , Paul Lukowicz

Irregularly sampled multivariate time series (ISMTS) are prevalent in reality. Most existing methods treat ISMTS as synchronized regularly sampled time series with missing values, neglecting that the irregularities are primarily attributed…

Machine Learning · Computer Science 2024-12-03 Jiexi Liu , Meng Cao , Songcan Chen

Multivariate time series alignment is critical for ensuring coherent analysis across variables, but missing values and timestamp inconsistencies make this task highly challenging. Existing approaches often rely on prior imputation, which…

Databases · Computer Science 2025-12-23 Ding Jia , Jingyu Zhu , Yu Sun , Aoqian Zhang , Shaoxu Song , Haiwei Zhang , Xiaojie Yuan

Linear causal analysis is central to a wide range of important application spanning finance, the physical sciences, and engineering. Much of the existing literature in linear causal analysis operates in the time domain. Unfortunately, the…

Machine Learning · Computer Science 2016-03-11 Francois W. Belletti , Evan R. Sparks , Michael J. Franklin , Alexandre M. Bayen , Joseph E. Gonzalez

Many modern time-series datasets contain large numbers of output response variables sampled for prolonged periods of time. For example, in neuroscience, the activities of 100s-1000's of neurons are recorded during behaviors and in response…

Machine Learning · Computer Science 2022-03-15 Rui Meng , Kristofer Bouchard

Since with massive data growth, the need for autonomous and generic anomaly detection system is increased. However, developing one stand-alone generic anomaly detection system that is accurate and fast is still a challenge. In this paper,…

Machine Learning · Computer Science 2018-12-03 Sooyeon Lee , Huy Kang Kim

Irregularly sampled time series (ISTS) data has irregular temporal intervals between observations and different sampling rates between sequences. ISTS commonly appears in healthcare, economics, and geoscience. Especially in the medical…

Machine Learning · Computer Science 2020-10-27 Chenxi Sun , Shenda Hong , Moxian Song , Hongyan Li

Anomaly detection is widely used in network intrusion detection, autonomous driving, medical diagnosis, credit card frauds, etc. However, several key challenges remain open, such as lack of ground truth labels, presence of complex temporal…

Machine Learning · Computer Science 2023-03-24 Shyam Sundar Saravanan , Tie Luo , Mao Van Ngo

The integrity of time series data in smart grids is often compromised by missing values due to sensor failures, transmission errors, or disruptions. Gaps in smart meter data can bias consumption analyses and hinder reliable predictions,…

Artificial Intelligence · Computer Science 2025-02-21 Amir Sartipi , Joaquín Delgado Fernández , Sergio Potenciano Menci , Alessio Magitteri

Accurate imputation is essential for the reliability and success of downstream tasks. Recently, diffusion models have attracted great attention in this field. However, these models neglect the latent distribution in a lower-dimensional…

Machine Learning · Computer Science 2024-09-16 Guojun Liang , Najmeh Abiri , Atiye Sadat Hashemi , Jens Lundström , Stefan Byttner , Prayag Tiwari

Efficient simulation of SDEs is essential in many applications, particularly for ergodic systems that demand efficient simulation of both short-time dynamics and large-time statistics. However, locally Lipschitz SDEs often require special…

Numerical Analysis · Mathematics 2021-02-26 Xingjie Li , Fei Lu , Felix X. -F. Ye

We are sometimes forced to use the Interrupted Time Series (ITS) design as an identification strategy for potential policy change, such as when we only have a single treated unit and no comparable controls. For example, with recent county-…

Methodology · Statistics 2020-02-17 Luke Miratrix

Time series imputation is one of the most challenge problems and has broad applications in various fields like health care and the Internet of Things. Existing methods mainly aim to model the temporally latent dependencies and the…

Machine Learning · Computer Science 2025-05-13 Ruichu Cai , Kaitao Zheng , Junxian Huang , Zijian Li , Zhengming Chen , Boyan Xu , Zhifeng Hao

Sampling is a fundamental technique, and sampling without replacement is often desirable when duplicate samples are not beneficial. Within machine learning, sampling is useful for generating diverse outputs from a trained model. We present…

Machine Learning · Computer Science 2021-07-21 Kensen Shi , David Bieber , Charles Sutton

Real-world time series data often present recurrent or repetitive patterns and it is often generated in real time, such as transportation passenger volume, network traffic, system resource consumption, energy usage, and human gait.…

Machine Learning · Computer Science 2021-05-05 Ming-Chang Lee , Jia-Chun Lin , Ernst Gunnar Gran

Time series with missing or irregularly sampled data are a persistent challenge in machine learning. Many methods operate on the frequency-domain, relying on the Fast Fourier Transform (FFT) which assumes uniform sampling, therefore…

Machine Learning · Computer Science 2025-06-23 Elizabeth Fons , Alejandro Sztrajman , Yousef El-Laham , Luciana Ferrer , Svitlana Vyetrenko , Manuela Veloso