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 Statistical Learning


How is Machine Learning Different from Statistics and Why it Matters

#artificialintelligence

As noted in the paper Derisking ML and AI by McKinsey [4], ML algorithms are typically far more complex than their statistical counterparts and often require design decisions to be made before the training process begins. The benefits of ML include superior performance and accuracy but their complexity leads to an added layer of challenge of interpretation, bias and compliance for ML. This is not just a technical problem though. The paper rightly points out that the degree of interpretability required is a policy choice. Feature Engineering -- ML is more complex because of the inherent difficulty of feature engineering -- that is, which features to use? How sound is each feature? Is it consistent with policy?


45 Best Data Science Certification for Data Scientists JA Directives

#artificialintelligence

Are you looking for Best Data Science Degree Online? This Online Data Science Course list will help you to become a top Data Scientist. Data science or data-driven science is one of today's fastest-growing fields. Do you want to become a Data Scientist in 2019? The list of the Data Science Degree will give you a clear idea from data science definition to expert's levels. If you don't know how to get data scientist certification then this data science certificate programs online will help you to get an online data science certificate. You will be able to get Microsoft data science certification or even Harvard data science certificate with this excellent collection of online courses. Also, this Data Science training will give you an idea about data science, python, data scientist, big data, analytics, machine learning, deep learning and Artificial Intelligence (AI) which are the most booming topics now. You can be a data science master in a short period of time. All big companies, publishers, advertisers, and other industries are now highly depended on data science or machine learning. So, it is high time to learn some skills in data science, for example, get the high demanded Data Science online certifications. How does it work at the present time, why data scientist's career and data science jobs are in top position? If you like a trendy career, you have that opportunity right now and get hired by the big industries. At the same time, online entrepreneurs and business personals also need to update themselves with the fundamental machine learning skills to compete with the fast-moving industry. Below are few best Data Science online courses that might assist you to jump-start the knowledge of data science sector. Best Data Science online tutorial and programs listing displays the'Best Course,' 'Product Description,' 'Rating,' 'Students Enrolled' 'Product's Image' and as well as an Enroll button to purchase the Courses from respective learning platforms for your convenience. Description: If you want to become a successful data scientist then you should take this best data science course. Just learning statistics, data visualization and data wrangling is not enough. You also need to know how to ask the right questions and tell the right story from your data. Description: This is an intermediate level data science course. Here you are going to learn to implement the advance data science concepts like inferential statistics and machine learning. The best data science certification promises you to get hired by a corporation after doing this course. As first you do the course then pay for it only if you get a data science job. So making an investment in your learning is completely risk-free now. You are going to master the foundational skills that are needed for you to do a job in the data science industry.


The F-Test for Regression Analysis

#artificialintelligence

Suppose by means of some analysis, we were to deduce that today's value of the DJIA Closing Price may turn out to be a good predictor of tomorrow's Closing Price. To test this theory, we will develop a linear regression model consisting of a single regression variable. This variable will be the time lagged value of the time series. Here are the first few rows of the modified Data Frame. Let's remove the first row to get rid of the NaN: Next let's create our training and test data sets: Plot the model's performance against the test data set: At first glance, this model's performance looks much better than what we got from the mean model.


Harnessing the Power of Infinitely Wide Deep Nets on Small-data Tasks

arXiv.org Machine Learning

Recent research shows that the following two models are equivalent: (a) infinitely wide neural networks (NNs) trained under l2 loss by gradient descent with infinitesimally small learning rate (b) kernel regression with respect to so-called Neural Tangent Kernels (NTKs) (Jacot et al., 2018). An efficient algorithm to compute the NTK, as well as its convolutional counterparts, appears in Arora et al. (2019a), which allowed studying performance of infinitely wide nets on datasets like CIFAR-10. However, super-quadratic running time of kernel methods makes them best suited for small-data tasks. We report results suggesting neural tangent kernels perform strongly on low-data tasks. 1. On a standard testbed of classification/regression tasks from the UCI database, NTK SVM beats the previous gold standard, Random Forests (RF), and also the corresponding finite nets. 2. On CIFAR-10 with 10 - 640 training samples, Convolutional NTK consistently beats ResNet-34 by 1% - 3%. 3. On VOC07 testbed for few-shot image classification tasks on ImageNet with transfer learning (Goyal et al., 2019), replacing the linear SVM currently used with a Convolutional NTK SVM consistently improves performance. 4. Comparing the performance of NTK with the finite-width net it was derived from, NTK behavior starts at lower net widths than suggested by theoretical analysis(Arora et al., 2019a). NTK's efficacy may trace to lower variance of output.


Minimizing a Sum of Clipped Convex Functions

arXiv.org Machine Learning

We consider the problem of minimizing a sum of clipped convex functions; applications include clipped empirical risk minimization and clipped control. While the problem of minimizing the sum of clipped convex functions is NP-hard, we present some heuristics for approximately solving instances of these problems. These heuristics can be used to find good, if not global, solutions and appear to work well in practice. We also describe an alternative formulation, based on the perspective transformation, which makes the problem amenable to mixed-integer convex programming and yields computationally tractable lower bounds. We illustrate one of our heuristic methods by applying it to various examples and use the perspective transformation to certify that the solutions are relatively close to the global optimum. This paper is accompanied by an open-source implementation.


Pre-train and Learn: Preserve Global Information for Graph Neural Networks

arXiv.org Machine Learning

China Abstract Graph neural networks (GNNs) have shown great power in learning on attributed graphs. However, it is still a challenge for GNNs to utilize information faraway from the source node. Moreover, general GNNs require graph attributes as input, so they cannot be appled to plain graphs. In the paper, we propose new models named G-GNNs (Global information for GNNs) to address the above limitations. First, the global structure and attribute features for each node are obtained via unsupervised pre-training, which preserve the global information associated to the node. Then, using the global features and the raw network attributes, we propose a parallel framework of GNNs to learn different aspects from these features. The proposed learning methods can be applied to both plain graphs and attributed graphs. Extensive experiments have shown that G-GNNs can outperform other state-of-the-art models on three standard evaluation graphs. Specially, our methods establish new benchmark records on Cora (84.31%) and Pubmed (80.95%) when learning on attributed graphs. 1 Introduction Semi-supervised learning on graphs aims to recover the labels for all nodes, while only very small proportion of node labels are given. The setting is popular in various of real world applications, since many labels are often expensive and difficult to collect.


Locality-Sensitive Hashing for f-Divergences: Mutual Information Loss and Beyond

arXiv.org Machine Learning

Computing approximate nearest neighbors in high dimensional spaces is a central problem in large-scale data mining with a wide range of applications in machine learning and data science. A popular and effective technique in computing nearest neighbors approximately is the locality-sensitive hashing (LSH) scheme. In this paper, we aim to develop LSH schemes for distance functions that measure the distance between two probability distributions, particularly for f-divergences as well as a generalization to capture mutual information loss. First, we provide a general framework to design LHS schemes for f-divergence distance functions and develop LSH schemes for the generalized Jensen-Shannon divergence and triangular discrimination in this framework. We show a two-sided approximation result for approximation of the generalized Jensen-Shannon divergence by the Hellinger distance, which may be of independent interest. Next, we show a general method of reducing the problem of designing an LSH scheme for a Krein kernel (which can be expressed as the difference of two positive definite kernels) to the problem of maximum inner product search. We exemplify this method by applying it to the mutual information loss, due to its several important applications such as model compression.


Variable Selection with Copula Entropy

arXiv.org Machine Learning

Variable selection is of significant importance for classification and regression tasks in machine learning and statistical applications where both predictability and explainability are needed. In this paper, a Copula Entropy (CE) based method for variable selection which use CE based ranks to select variables is proposed. The method is both model-free and tuning-free. Comparison experiments between the proposed method and traditional variable selection methods, such as Stepwise Selection, regularized generalized linear models and Adaptive LASSO, were conducted on the UCI heart disease data. Experimental results show that CE based method can select the `right' variables out effectively and derive better interpretable results than traditional methods do without sacrificing accuracy performance. It is believed that CE based variable selection can help to build more explainable models.


Landmark Ordinal Embedding

arXiv.org Machine Learning

In this paper, we aim to learn a low-dimensional Euclidean representation from a set of constraints of the form "item j is closer to item i than item k". Existing approaches for this "ordinal embedding" problem require expensive optimization procedures, which cannot scale to handle increasingly larger datasets. To address this issue, we propose a landmark-based strategy, which we call Landmark Ordinal Embedding (LOE). Our approach trades off statistical efficiency for computational efficiency by exploiting the low-dimensionality of the latent embedding. We derive bounds establishing the statistical consistency of LOE under the popular Bradley-Terry-Luce noise model. Through a rigorous analysis of the computational complexity, we show that LOE is significantly more efficient than conventional ordinal embedding approaches as the number of items grows. We validate these characterizations empirically on both synthetic and real datasets. We also present a practical approach that achieves the "best of both worlds", by using LOE to warm-start existing methods that are more statistically efficient but computationally expensive.


Conditional Expectation Propagation

arXiv.org Machine Learning

Expectation propagation (EP) is a powerful approximate inference algorithm. However, a critical barrier in applying EP is that the moment matching in message updates can be intractable. Handcrafting approximations is usually tricky, and lacks generalizability. Importance sampling is very expensive. While Laplace propagation provides a good solution, it has to run numerical optimizations to find Laplace approximations in every update, which is still quite inefficient. To overcome these practical barriers, we propose conditional expectation propagation (CEP) that performs conditional moment matching given the variables outside each message, and then takes expectation w.r.t the approximate posterior of these variables. The conditional moments are often analytical and much easier to derive. In the most general case, we can use (fully) factorized messages to represent the conditional moments by quadrature formulas. We then compute the expectation of the conditional moments via Taylor approximations when necessary. In this way, our algorithm can always conduct efficient, analytical fixed point iterations. Experiments on several popular models for which standard EP is available or unavailable demonstrate the advantages of CEP in both inference quality and computational efficiency.