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 Statistical Learning


Bayesian Optimal Design of Experiments For Inferring The Statistical Expectation Of A Black-Box Function

arXiv.org Machine Learning

Bayesian optimal design of experiments (BODE) has been successful in acquiring information about a quantity of interest (QoI) which depends on a black-box function. BODE is characterized by sequentially querying the function at specific designs selected by an infill-sampling criterion. However, most current BODE methods operate in specific contexts like optimization, or learning a universal representation of the black-box function. The objective of this paper is to design a BODE for estimating the statistical expectation of a physical response surface. This QoI is omnipresent in uncertainty propagation and design under uncertainty problems. Our hypothesis is that an optimal BODE should be maximizing the expected information gain in the QoI. We represent the information gain from a hypothetical experiment as the Kullback-Liebler (KL) divergence between the prior and the posterior probability distributions of the QoI. The prior distribution of the QoI is conditioned on the observed data and the posterior distribution of the QoI is conditioned on the observed data and a hypothetical experiment. The main contribution of this paper is the derivation of a semi-analytic mathematical formula for the expected information gain about the statistical expectation of a physical response. The developed BODE is validated on synthetic functions with varying number of input-dimensions. We demonstrate the performance of the methodology on a steel wire manufacturing problem.


On Inductive Abilities of Latent Factor Models for Relational Learning

Journal of Artificial Intelligence Research

Latent factor models are increasingly popular for modeling multi-relational knowledge graphs. By their vectorial nature, it is not only hard to interpret why this class of models works so well, but also to understand where they fail and how they might be improved. We conduct an experimental survey of state-of-the-art models, not towards a purely comparative end, but as a means to get insight about their inductive abilities. To assess the strengths and weaknesses of each model, we create simple tasks that exhibit first, atomic properties of binary relations, and then, common inter-relational inference through synthetic genealogies. Based on these experimental results, we propose new research directions to improve on existing models.


Predicting Individual Responses to Vasoactive Medications in Children with Septic Shock

arXiv.org Machine Learning

Objective: Predict individual septic children's personalized physiologic responses to vasoactive titrations by training a Recurrent Neural Network (RNN) using EMR data. Materials and Methods: This study retrospectively analyzed EMR of patients admitted to a pediatric ICU from 2009 to 2017. Data included charted time series vitals, labs, drugs, and interventions of children with septic shock treated with dopamine, epinephrine, or norepinephrine. A RNN was trained to predict responses in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) to 8,640 titrations during 652 septic episodes and evaluated on a holdout set of 3,883 titrations during 254 episodes. A linear regression model using titration data as its sole input was also developed and compared to the RNN model. Evaluation methods included the correlation coefficient between actual physiologic responses and RNN predictions, mean absolute error (MAE), and area under the receiver operating characteristic curve (AUC). Results: The actual physiologic responses displayed significant variability and were more accurately predicted by the RNN model than by titration alone (r=0.20 vs r=0.05, p<0.01). The RNN showed MAE and AUC improvements over the linear model. The RNN's MAEs associated with dopamine and epinephrine were 1-3% lower than the linear regression model MAE for HR, SBP, DBP, and MAP. Across all vitals vasoactives, the RNN achieved 1-19% AUC improvement over the linear model. Conclusion: This initial attempt in pediatric critical care to predict individual physiologic responses to vasoactive dose changes in children with septic shock demonstrated an RNN model showed some improvement over a linear model. While not yet clinically applicable, further development may assist clinical administration of vasoactive medications in children with septic shock.


Conditional deep surrogate models for stochastic, high-dimensional, and multi-fidelity systems

arXiv.org Machine Learning

We present a probabilistic deep learning methodology that enables the construction of predictive data-driven surrogates for stochastic systems. Leveraging recent advances in variational inference with implicit distributions, we put forth a statistical inference framework that enables the end-to-end training of surrogate models on paired input-output observations that may be stochastic in nature, originate from different information sources of variable fidelity, or be corrupted by complex noise processes. The resulting surrogates can accommodate high-dimensional inputs and outputs and are able to return predictions with quantified uncertainty. The effectiveness our approach is demonstrated through a series of canonical studies, including the regression of noisy data, multi-fidelity modeling of stochastic processes, and uncertainty propagation in high-dimensional dynamical systems.


Semi-supervised Learning with Graphs: Covariance Based Superpixels For Hyperspectral Image Classification

arXiv.org Machine Learning

ABSTRACT In this paper, we present a graph-based semi-supervised framework for hyperspectral image classification. We first introduce a novel superpixel algorithm based on the spectral covariance matrix representation of pixels to provide a better representation of our data. We then construct a superpixel graph, based on carefully considered feature vectors, before performing classification. We demonstrate, through a set of experimental results using two benchmarking datasets, that our approach outperforms three state-of-the-art classification frameworks, especially when a extremely small amount of labelled data is used. Index Terms-- Hyperspectral Imaging, Superpixels, Covariance, Graphs,Semi-Supervised Learning, Classification 1. INTRODUCTION Hyperspectral image (HSI) classification is an active area of research and poses unique challenges.


High-Fidelity Vector Space Models of Structured Data

arXiv.org Artificial Intelligence

Machine learning systems regularly deal with structured data in real-world applications. Unfortunately, such data has been difficult to faithfully represent in a way that most machine learning techniques would expect, i.e. as a real-valued vector of a fixed, pre-specified size. In this work, we introduce a novel approach that compiles structured data into a satisfiability problem which has in its set of solutions at least (and often only) the input data. The satisfiability problem is constructed from constraints which are generated automatically a priori from a given signature, thus trivially allowing for a bag-of-words-esque vector representation of the input to be constructed. The method is demonstrated in two areas, automated reasoning and natural language processing, where it is shown to produce vector representations of natural-language sentences and first-order logic clauses that can be precisely translated back to their original, structured input forms.


Machine Learning in Python - PyImageSearch

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Struggling to get started with machine learning using Python? In this step-by-step, hands-on tutorial you will learn how to perform machine learning using Python on numerical data and image data. By the time you are finished reading this post, you will be able to get your start in machine learning. To launch your machine learning in Python education, just keep reading! Inside this tutorial, you will learn how to perform machine learning in Python on numerical data and image data. Using this technique you will be able to get your start with machine learning and Python! Along the way, you'll discover popular machine learning algorithms that you can use in your own projects as well, including: This hands-on experience will give you the knowledge (and confidence) you need to apply machine learning in Python to your own projects. Before we can get started with this tutorial you first need to make sure your system is configured for machine learning. Today's code requires the following libraries: In order to help you gain experience performing machine learning in Python, we'll be working with two separate datasets. The first one, the Iris dataset, is the machine learning practitioner's equivalent of "Hello, World!" (likely one of the first pieces of software you wrote when learning how to program). The second dataset, 3-scenes, is an example image dataset I put together -- this dataset will help you gain experience working with image data, and most importantly, learn what techniques work best for numerical/categorical datasets vs. image datasets. Let's go ahead and get a more intimate look at these datasets.


Data Dimensionality Reduction in the Age of Machine Learning - DATAVERSITY

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Click to learn more about author Rosaria Silipo. Machine Learning is all the rage as companies try to make sense of the mountains of data they are collecting. Data is everywhere and proliferating at unprecedented speed. But, more data is not always better. In fact, large amounts of data can not only considerably slow down the system execution but can sometimes even produce worse performances in Data Analytics applications.


The Most Intuitive and Easiest Guide for Artificial Neural Network

#artificialintelligence

Anyone who is living in a world of 2019, would have heard of these words more than once. And you probably have seen the awesome works such as image classification, computer vision, and speech recognition. So are you also interested in building those cool AI project but still have no idea of what artificial neural network is? There are already hundreds of articles explaining the concept of the artificial neural network with the name of "a beginner's guide on back propagation in ANN" or "A gentle introduction of the artificial neural network." They are really great already, but I found It could be still hard for someone who is not comfortable with mathematical expressions.