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 Statistical Learning


Learning a Single Neuron with Bias Using Gradient Descent

arXiv.org Machine Learning

We theoretically study the fundamental problem of learning a single neuron with a bias term ($\mathbf{x} \mapsto \sigma(<\mathbf{w},\mathbf{x}> + b)$) in the realizable setting with the ReLU activation, using gradient descent. Perhaps surprisingly, we show that this is a significantly different and more challenging problem than the bias-less case (which was the focus of previous works on single neurons), both in terms of the optimization geometry as well as the ability of gradient methods to succeed in some scenarios. We provide a detailed study of this problem, characterizing the critical points of the objective, demonstrating failure cases, and providing positive convergence guarantees under different sets of assumptions. To prove our results, we develop some tools which may be of independent interest, and improve previous results on learning single neurons.


Evaluation Metrics for Graph Generative Models: Problems, Pitfalls, and Practical Solutions

arXiv.org Machine Learning

Graph generative models are a highly active branch of machine learning. Given the steady development of new models of ever-increasing complexity, it is necessary to provide a principled way to evaluate and compare them. In this paper, we enumerate the desirable criteria for comparison metrics, discuss the development of such metrics, and provide a comparison of their respective expressive power. We perform a systematic evaluation of the main metrics in use today, highlighting some of the challenges and pitfalls researchers inadvertently can run into. We then describe a collection of suitable metrics, give recommendations as to their practical suitability, and analyse their behaviour on synthetically generated perturbed graphs as well as on recently proposed graph generative models.


Testing Group Fairness via Optimal Transport Projections

arXiv.org Machine Learning

We present a statistical testing framework to detect if a given machine learning classifier fails to satisfy a wide range of group fairness notions. The proposed test is a flexible, interpretable, and statistically rigorous tool for auditing whether exhibited biases are intrinsic to the algorithm or due to the randomness in the data. The statistical challenges, which may arise from multiple impact criteria that define group fairness and which are discontinuous on model parameters, are conveniently tackled by projecting the empirical measure onto the set of group-fair probability models using optimal transport. This statistic is efficiently computed using linear programming and its asymptotic distribution is explicitly obtained. The proposed framework can also be used to test for testing composite fairness hypotheses and fairness with multiple sensitive attributes. The optimal transport testing formulation improves interpretability by characterizing the minimal covariate perturbations that eliminate the bias observed in the audit.


Contrastive ACE: Domain Generalization Through Alignment of Causal Mechanisms

arXiv.org Machine Learning

Domain generalization aims to learn knowledge invariant across different distributions while semantically meaningful for downstream tasks from multiple source domains, to improve the model's generalization ability on unseen target domains. The fundamental objective is to understand the underlying "invariance" behind these observational distributions and such invariance has been shown to have a close connection to causality. While many existing approaches make use of the property that causal features are invariant across domains, we consider the causal invariance of the average causal effect of the features to the labels. This invariance regularizes our training approach in which interventions are performed on features to enforce stability of the causal prediction by the classifier across domains. Our work thus sheds some light on the domain generalization problem by introducing invariance of the mechanisms into the learning process. Experiments on several benchmark datasets demonstrate the performance of the proposed method against SOTAs.


An End-to-End Framework for Molecular Conformation Generation via Bilevel Programming

arXiv.org Artificial Intelligence

Predicting molecular conformations (or 3D structures) from molecular graphs is a fundamental problem in many applications. Most existing approaches are usually divided into two steps by first predicting the distances between atoms and then generating a 3D structure through optimizing a distance geometry problem. However, the distances predicted with such two-stage approaches may not be able to consistently preserve the geometry of local atomic neighborhoods, making the generated structures unsatisfying. In this paper, we propose an end-to-end solution for molecular conformation prediction called ConfVAE based on the conditional variational autoencoder framework. Specifically, the molecular graph is first encoded in a latent space, and then the 3D structures are generated by solving a principled bilevel optimization program. Extensive experiments on several benchmark data sets prove the effectiveness of our proposed approach over existing state-of-the-art approaches. Code is available at https://github.com/MinkaiXu/ConfVAE-ICML21


Generalized Linear Models

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Generalized Linear Model (GLiM, or GLM) is an advanced statistical modelling technique formulated by John Nelder and Robert Wedderburn in 1972. It is an umbrella term that encompasses many other models, which allows the response variable y to have an error distribution other than a normal distribution. The models include Linear Regression, Logistic Regression, and Poisson Regression. The underlying relationship between the response and the predictors is linear (i.e. Also, the error distribution of the response variable should be normally distributed.


7 Best Advanced Data Science Courses in 2021

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Are you a working professional and looking for the best advanced data science courses? If yes, then you are in the right place. In this article, you will find the 7 Best Data Science Courses for Working Professionals. To gain data science skills, there are numerous courses available. So, without wasting your time, let's start finding the Best Data Science Courses for Working Professionalsโ€“ This is a Nano-Degree Program offered by Udacity.


Regression analysis using Python

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This article was written by Stuart Reid. This tutorial covers regression analysis using the Python StatsModels package with Quandl integration. For motivational purposes, here is what we are working towards: a regression analysis program which receives multiple data-set names from Quandl.com, automatically downloads the data, analyses it, and plots the results in a new window. Linear regression analysis fits a straight line to some data in order to capture the linear relationship between that data. The regression line is constructed by optimizing the parameters of the straight line function such that the line best fits a sample of (x, y) observations where y is a variable dependent on the value of x.


Gradient Descent Algorithm : Understanding the Logic - Analytics Vidhya

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Gradient Descent algorithm is an iterative algorithm used for the optimization of parameters used in an equation and to decrease the Loss (often called a Cost function). But before diving deep, we first need to have a basic idea of what a gradient means? Why are we calculating the gradient of a function and what is our final goal to achieve by using this algorithm? The gradient of a function refers to the slope of the function at some point. We are calculating the gradient of a function to achieve the global minima of the function.


How to Become a Machine Learning Specialist in Under 20 Hours from This FREE LinkedIn Course

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If you are interested to become a Machine Learning Specialist, you are in the right place, because here we have the best LinkedIn course that you will love it. Machine Learning proves to be the future of our civilization, something that will help us to elevate our achievements to the next level, and explore new things, and all in all increase the quality of our life. The job positions in Machine Learning areas are one of the highest paying in the whole IT industry due to the fact that it requires knowledge in Mathematics, Statistics, Computer Science, and Software Engineering all combined. Now, to gain knowledge in all of these fields can be time-consuming due to all of those are sciences in themselves. However, there are huge corporations that have a huge need for experts in these areas and do not have the time that it takes to create these experts as we've already mentioned.