24 research outputs found
Nonparametric Bivariate Distribution Estimation under Right Censoring using Poisson Polynomials
In this major paper, a nonparametric estimator of the joint cumulative distribution function using Poisson probability under right censoring was proposed and discussed. In particular, the joint cumulative distribution of two non-negative random variables X and Y was of interest in this work, where X was assumed to be complete, while Y was subjected to right censoring. The asymptotic properties of the proposed estimator (called hereafter Poisson polynomial estimator) were established, including independent and identically distributed representation, expectation and variance, and asymptotic normality.
Furthermore, two real datasets were analyzed to assess the Poisson polynomial estimator: Loss-ALAE joint distribution estimation and age’s impact on survival in patients with colon cancer. Also, the Stute empirical estimator and empirical Bernstein estimator were introduced as a comparison. Evidence reveals that the Poisson estimator gives a more precise value along with the best effect on smoothness among all three estimators and provides an alternative solution for future simulation and prediction. However, more calculations are required to obtain a precise solution with an acceptable error as the Poisson probability takes values from zero to infinity
Learning the Joint Representation of Heterogeneous Temporal Events for Clinical Endpoint Prediction
The availability of a large amount of electronic health records (EHR)
provides huge opportunities to improve health care service by mining these
data. One important application is clinical endpoint prediction, which aims to
predict whether a disease, a symptom or an abnormal lab test will happen in the
future according to patients' history records. This paper develops deep
learning techniques for clinical endpoint prediction, which are effective in
many practical applications. However, the problem is very challenging since
patients' history records contain multiple heterogeneous temporal events such
as lab tests, diagnosis, and drug administrations. The visiting patterns of
different types of events vary significantly, and there exist complex nonlinear
relationships between different events. In this paper, we propose a novel model
for learning the joint representation of heterogeneous temporal events. The
model adds a new gate to control the visiting rates of different events which
effectively models the irregular patterns of different events and their
nonlinear correlations. Experiment results with real-world clinical data on the
tasks of predicting death and abnormal lab tests prove the effectiveness of our
proposed approach over competitive baselines.Comment: 8 pages, this paper has been accepted by AAAI 201
Towards Long-Tailed Recognition for Graph Classification via Collaborative Experts
Graph classification, aiming at learning the graph-level representations for
effective class assignments, has received outstanding achievements, which
heavily relies on high-quality datasets that have balanced class distribution.
In fact, most real-world graph data naturally presents a long-tailed form,
where the head classes occupy much more samples than the tail classes, it thus
is essential to study the graph-level classification over long-tailed data
while still remaining largely unexplored. However, most existing long-tailed
learning methods in visions fail to jointly optimize the representation
learning and classifier training, as well as neglect the mining of the
hard-to-classify classes. Directly applying existing methods to graphs may lead
to sub-optimal performance, since the model trained on graphs would be more
sensitive to the long-tailed distribution due to the complex topological
characteristics. Hence, in this paper, we propose a novel long-tailed
graph-level classification framework via Collaborative Multi-expert Learning
(CoMe) to tackle the problem. To equilibrate the contributions of head and tail
classes, we first develop balanced contrastive learning from the view of
representation learning, and then design an individual-expert classifier
training based on hard class mining. In addition, we execute gated fusion and
disentangled knowledge distillation among the multiple experts to promote the
collaboration in a multi-expert framework. Comprehensive experiments are
performed on seven widely-used benchmark datasets to demonstrate the
superiority of our method CoMe over state-of-the-art baselines.Comment: Accepted by IEEE Transactions on Big Data (TBD 2024
Redundancy-Free Self-Supervised Relational Learning for Graph Clustering
Graph clustering, which learns the node representations for effective cluster
assignments, is a fundamental yet challenging task in data analysis and has
received considerable attention accompanied by graph neural networks in recent
years. However, most existing methods overlook the inherent relational
information among the non-independent and non-identically distributed nodes in
a graph. Due to the lack of exploration of relational attributes, the semantic
information of the graph-structured data fails to be fully exploited which
leads to poor clustering performance. In this paper, we propose a novel
self-supervised deep graph clustering method named Relational Redundancy-Free
Graph Clustering (RFGC) to tackle the problem. It extracts the attribute-
and structure-level relational information from both global and local views
based on an autoencoder and a graph autoencoder. To obtain effective
representations of the semantic information, we preserve the consistent
relation among augmented nodes, whereas the redundant relation is further
reduced for learning discriminative embeddings. In addition, a simple yet valid
strategy is utilized to alleviate the over-smoothing issue. Extensive
experiments are performed on widely used benchmark datasets to validate the
superiority of our RFGC over state-of-the-art baselines. Our codes are
available at https://github.com/yisiyu95/R2FGC.Comment: Accepted by IEEE Transactions on Neural Networks and Learning Systems
(TNNLS 2024