Statistical Learning
Understanding Self-supervised Learning with Dual Deep Networks
Tian, Yuandong, Yu, Lantao, Chen, Xinlei, Ganguli, Surya
We propose a novel theoretical framework to understand self-supervised learning methods that employ dual pairs of deep ReLU networks (e.g., SimCLR, BYOL). First, we prove that in each SGD update of SimCLR with various loss functions (simple contrastive loss, soft Triplet loss and InfoNCE loss), the weights at each layer are updated by a covariance operator that specifically amplifies initial random selectivities that vary across data samples but survive averages over data augmentations. We show this leads to the emergence of hierarchical features, if the input data are generated from a hierarchical latent tree model. With the same framework, we also show analytically that in BYOL, the combination of Batch-Norm and a predictor network creates an implicit contrastive term, acting as an approximate covariance operator. Additionally, for linear architectures we derive exact solutions for BYOL that provide conceptual insights into how BYOL can learn useful non-collapsed representations without any contrastive terms that separate negative pairs. Extensive ablation studies justify our theoretical findings. Unlike supervised learning (SL) that deals with labeled data, SSL learns meaningful structures from randomly initialized networks without human-provided labels. In this paper, we propose a systematic theoretical analysis of SSL with deep ReLU networks. Our analysis imposes no parametric assumptions on the input data distribution and is applicable to stateof-the-art SSL methods that typically involve two parallel (or dual) deep ReLU networks during training (e.g., SimCLR (Chen et al., 2020a), BYOL (Grill et al., 2020), etc). We do so by developing an analogy between SSL and a theoretical framework for analyzing supervised learning, namely the student-teacher setting (Tian, 2020; Allen-Zhu and Li, 2020; Lampinen and Ganguli, 2018; Saad and Solla, 1996), which also employs a pair of dual networks.
Time Series Analysis 102
While building a forecast model the available data is generally divided into 2 sets -- training set and validation/test set. The training set is used to learn the model. The learned model is then used to forecast for the test set period. The accuracy is then calculated using the actual and forecasted values for the test set. The accuracy calculated on an unseen data gives an idea about how the model would perform in the real world on the future data.
A Gentle Introduction to Nonparametric Statistics
A large portion of the field of statistics and statistical methods is dedicated to data where the distribution is known. Samples of data where we already know or can easily identify the distribution of are called parametric data. Often, parametric is used to refer to data that was drawn from a Gaussian distribution in common usage. Data in which the distribution is unknown or cannot be easily identified is called nonparametric. In the case where you are working with nonparametric data, specialized nonparametric statistical methods can be used that discard all information about the distribution.
The Perfect Recipe for Classification Using Logistic Regression
Supervised Learning is an essential part of Machine Learning. Classification techniques are used when the variable to be predicted is categorical. A common example of classification problem is trying to classify an Iris flower among its three different species. Logistic regression is a classification technique borrowed by machine learning from the field of statistics. Logistic Regression is a statistical method for analyzing a dataset in which there are one or more independent variables that determine an outcome.
Top 25 Best Machine Learning Books You Should Read
Machine Learning foners Second Edition has been written and designed for absolute beginners. This means plain-English explanations and no coding experience required. Where core algorithms are introduced, clear explanations and visual examples are added to make it easy and engaging to follow along at home. This major new edition features many topics not covered in the First Edition, including Cross Validation, Data Scrubbing and Ensemble Modeling.
Data Science & Deep Learning for Business 20 Case Studies
All MBA's will preach that Data-Driven Methods udemy discount Understand the value of data for businesses Learn to use Python, Pandas, Matplotlib & Seaborn, SkLearn, Keras, Tensorflow, NLTK, Prophet, PySpark, MLLib and more! Apply Data Science in Marketing to improve Conversion Rates, Predict Engagement and Customer Life Time Value Machine Learning from Linear Regressions (polynomial & multivariate), K-NNs, Logistic Regressions, SVMs, Decision Trees & Random Forests Unsupervised Machine Learning with K-Means, Mean-Shift, DBSCAN, EM with GMMs, PCA and t-SNE Build a Product Recommendation Tool using collaborative & item/content based Hypothesis Testing and A/B Testing - Understand t-tests and p values Natural Langauge Processing - Summarize Reviews, Sentiment Analysis on Airline Tweets & Spam Detection To use Google Colab's iPython notebooks for fast, relaible cloud based data science work Deploy your Machine Learning Models on the cloud using AWS This course takes on Machine Learning and Statistical theory and teaches you to use it in solving 20 real-world Business problems. Data Scientist is the buzz of the 21st century for good reason! The tech revolution is just starting and Data Science is at the forefront. As a result, "Data Scientist has become the top job in the US for the last 4 years running!" according to Harvard Business Review & Glassdoor.
Logistic Regression for Beginners - A Complete Guide - Let's Discuss Stuff
Logistic Regression is the most widely used classification algorithm in machine learning. It is used in many real-world scenarios like spam detected, cancer detection, IRIS dataset, etc. Mostly it is used in binary classification problems. But it can also be used in multiclass classification. Logistic Regression predicts the probability that the given data point belongs to a certain class or not. In this article, I will be using the famous heart disease dataset from Kaggle. In this dataset, the main goal is to predict whether the given person has heart disease or not.
Machine Learning in a Nutshell
Machine Learning, Artificial intelligence (AI) and Deep Learning are taking the world by storm, dominating conversations about how machines can replace humans by providing a competitive advantage to businesses. The World is currently preparing to enter the fourth industrial revolution -- the rise of the "intelligent machine." At the heart of this revolution is Artificial Intelligence (AI), Mimicking human cognitive functions like problem-solving, learning and decision making using algorithms. From speed to efficiency, AI offers an abundance of benefits. Numerous sectors, including healthcare, automotive, defence and retail have already witnessed the game-changing impact of AI.
Neural Bridge Sampling for Evaluating Safety-Critical Autonomous Systems
Sinha, Aman, O'Kelly, Matthew, Tedrake, Russ, Duchi, John
Learning-based methodologies increasingly find applications in safety-critical domains like autonomous driving and medical robotics. Due to the rare nature of dangerous events, real-world testing is prohibitively expensive and unscalable. In this work, we employ a probabilistic approach to safety evaluation in simulation, where we are concerned with computing the probability of dangerous events. We develop a novel rare-event simulation method that combines exploration, exploitation, and optimization techniques to find failure modes and estimate their rate of occurrence. We provide rigorous guarantees for the performance of our method in terms of both statistical and computational efficiency. Finally, we demonstrate the efficacy of our approach on a variety of scenarios, illustrating its usefulness as a tool for rapid sensitivity analysis and model comparison that are essential to developing and testing safety-critical autonomous systems.
A contribution to Optimal Transport on incomparable spaces
Optimal Transport is a theory that allows to define geometrical notions of distance between probability distributions and to find correspondences, relationships, between sets of points. Many machine learning applications are derived from this theory, at the frontier between mathematics and optimization. This thesis proposes to study the complex scenario in which the different data belong to incomparable spaces. In particular we address the following questions: how to define and apply Optimal Transport between graphs, between structured data? How can it be adapted when the data are varied and not embedded in the same metric space? This thesis proposes a set of Optimal Transport tools for these different cases. An important part is notably devoted to the study of the Gromov-Wasserstein distance whose properties allow to define interesting transport problems on incomparable spaces. More broadly, we analyze the mathematical properties of the various proposed tools, we establish algorithmic solutions to compute them and we study their applicability in numerous machine learning scenarii which cover, in particular, classification, simplification, partitioning of structured data, as well as heterogeneous domain adaptation.