Accuracy



MercurialMonkey/Harvard-University-Capstone-Project-Data-Science

#artificialintelligence

I have submitted my own project using a dataset of my choosing. My project has been reviewed both by my peers and the professor. I chose to work with Credit Card Fraud Detection, It is important that credit card companies are able to recognize fraudulent credit card transactions so that customers are not charged for items that they did not purchase. The datasets contains transactions made by credit cards in September 2013 by european cardholders. Due to imbalancing nature of the data, many observations could be predicted as False Negative, in this case Legal Transactions instead of Fraudolent Transaction.


Comparing Classifiers: Decision Trees, K-NN & Naive Bayes

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A myriad of options exist for classification. That said, three popular classification methods-- Decision Trees, k-NN & Naive Bayes--can be tweaked for practically every situation. Naive Bayes and K-NN, are both examples of supervised learning (where the data comes already labeled). Decision trees are easy to use for small amounts of classes. If you're trying to decide between the three, your best option is to take all three for a test drive on your data, and see which produces the best results.


Proof-of-concept system uses smart speakers to catch signs of cardiac arrest

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In an effort to tackle in-home cardiac arrest, University of Washington researchers have devised a novel contactless system that uses smartphones or voice-based personal assistants to identify telltale breathing patterns that accompany an attack. The proof-of-concept strategy, described in an NPJ Digital Medicine paper published this morning, involved a supervised machine learning model called a support-vector machine that was trained for use in the bedroom, a controlled environment in which the majority of in-home cardiac arrests occur. "Sometimes reported as'gasping' breaths, agonal respirations may hold potential as an audible diagnostic biomarker, particularly in unwitnessed cardiac arrests that occur in a private residence, the location of [two-thirds] of all [out-of-hospital cardiac arrests]," the researchers wrote. "The widespread adoption of smartphones and smart speakers (projected to be in 75% of US households by 2020) presents a unique opportunity to identify this audible biomarker and connect unwitnessed cardiac arrest victims to emergency medical services (EMS) or others who can administer cardiopulmonary resuscitation." Cross-validation analysis of the trained classifier yielded an overall sensitivity and specificity of 97.24% and 99.51%.


Novel AI Model Predicts Breast Cancer as well as Doctors

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Published today in the peer-reviewed journal Radiology, an IBM Research team created a new artificial intelligence (AI) model that can predict breast cancer malignancy and identify normal digital mammography exams as accurately as radiologists. Mammography, a low-dose x-ray procedure to image breasts, is considered the best breast cancer screening test available according to the American Cancer Society. However, mammograms are not always accurate. According to a U.S. 10-year study published in the New England Journal of Medicine, 23.8 percent of study participants had at least one false positive mammogram where breast cancer was not actually present. Furthermore, the American Cancer Society estimates that one in five screening mammograms are false-negatives that fail to detect existing breast cancer.


Local Bures-Wasserstein Transport: A Practical and Fast Mapping Approximation

arXiv.org Machine Learning

Optimal transport (OT)-based methods have a wide range of applications and have attracted a tremendous amount of attention in recent years. However, most of the computational approaches of OT do not learn the underlying transport map. Although some algorithms have been proposed to learn this map, they rely on kernel-based methods, which makes them prohibitively slow when the number of samples increases. Here, we propose a way to learn an approximate transport map and a parametric approximation of the Wasserstein barycenter. We build an approximated transport mapping by leveraging the closed-form of Gaussian (Bures-Wasserstein) transport; we compute local transport plans between matched pairs of the Gaussian components of each density. The learned map generalizes to out-of-sample examples. We provide experimental results on simulated and real data, comparing our proposed method with other mapping estimation algorithms. Preliminary experiments suggest that our proposed method is not only faster, with a factor 80 overall running time, but it also requires fewer components than state-of-the-art methods to recover the support of the barycenter. From a practical standpoint, it is straightforward to implement and can be used with a conventional machine learning pipeline.


Normalizing flows for novelty detection in industrial time series data

arXiv.org Machine Learning

Flow-based deep generative models learn data distributions by transforming a simple base distribution into a complex distribution via a set of invertible transformations. Due to the invertibility, such models can score unseen data samples by computing their exact likelihood under the learned distribution. This makes flow-based models a perfect tool for novelty detection, an anomaly detection technique where unseen data samples are classified as normal or abnormal by scoring them against a learned model of normal data. We show that normalizing flows can be used as novelty detectors in time series. Two flow-based models, Masked Autoregressive Flows and Free-form Jacobian of Reversible Dynamics restricted by autoregressive MADE networks, are tested on synthetic data and motor current data from an industrial machine and achieve good results, outperforming a conventional novelty detection method, the Local Outlier Factor.


Amazon's AI rewrites voice commands in natural language to reduce false positives

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"Reference resolution" is a considerable challenge in natural language processing -- in the context of AI assistants like Alexa, it entails correctly associating a word like "their" in the utterance like "play their latest album" with a given musician. Scientists at Amazon have previously addressed it by tapping AI that maps correspondences between variables used by different services, but these mappings tend to be application-specific and not particularly scalable. That's why now, researchers at the Seattle company are actively exploring a technique that rewrites commands in natural language by substituting names and other data for references (for instance, rewriting "Play their latest album" as "Play Imagine Dragons' latest album"). Given a word of an input sequence, their contextual query rewrite engine adds a word to an ouput sequence according to probabilities computed by the machine learning algorithm. They describe it in a paper ("Scaling Multi-Domain Dialogue State Tracking via Query Reformulation") that's scheduled to be presented at the North American chapter of the Association for Computational Linguistics.


Beware of data "science projects" turned fraud prevention solutions - IBM RegTech Innovations Blog

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As e-commerce has revolutionized the way we buy and sell online, we are no longer bounded by borders or time zones. Goods can be purchased from anywhere around the world at any time of day. Because of this, traditional rules-based fraud detection systems have become outdated and no longer work. Today, real-time payments require real-time fraud detection. Modern payment fraud schemes require modern prevention With so many transactions being done electronically, it's nearly impossible to have humans alone monitor these transactions and keep fraud and error rates down to acceptable levels.


Confidence intervals for class prevalences under prior probability shift

arXiv.org Machine Learning

Point estimation of class prevalences in the presence of data set shift has been a popular research topic for more than two decades. Less attention has been paid to the construction of confidence and prediction intervals for estimates of class prevalences. One little considered question is whether or not it is necessary for practical purposes to distinguish confidence and prediction intervals. Another question so far not yet conclusively answered is whether or not the discriminatory power of the classifier or score at the basis of an estimation method matters for the accuracy of the estimates of the class prevalences. This paper presents a simulation study aimed at shedding some light on these and other related questions.