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 Statistical Learning


Federated $f$-Differential Privacy

arXiv.org Artificial Intelligence

Unlike traditional distributed training approaches that upload all the data to central servers, federated learning performs ondevice training and only some summaries of local data or local models are exchanged among clients. Typically, the clients upload their local models to the server and share the global averaging in a repeated manner. This offers plausible solutions to address the critical data privacy issue: sensitive information about individuals such as typing history, shopping transactions, geographical locations, medical records, would stay localized. Nonetheless, a malicious client who participates in the federated learning might still be able to learn information about the other clients' data through the shared model's weights. This is because it is possible for an adversary to learn about or even identify certain individuals by simply tweaking the input datasets and probing the output of the algorithm [FJR15, SSSS17]. This gives rise to a pressing call for privacy-preserving federated learning algorithms. Accordingly, we urgently need a rigorous and principled framework to enhance data privacy, and to quantitatively answer the important questions: Can another client identify the presence or absence of any individual record in my data in federated learning? Worse, what if all the other clients ally each other to attack my data?


Towards Causal Representation Learning

arXiv.org Artificial Intelligence

The two fields of machine learning and graphical causality arose and developed separately. However, there is now cross-pollination and increasing interest in both fields to benefit from the advances of the other. In the present paper, we review fundamental concepts of causal inference and relate them to crucial open problems of machine learning, including transfer and generalization, thereby assaying how causality can contribute to modern machine learning research. This also applies in the opposite direction: we note that most work in causality starts from the premise that the causal variables are given. A central problem for AI and causality is, thus, causal representation learning, the discovery of high-level causal variables from low-level observations. Finally, we delineate some implications of causality for machine learning and propose key research areas at the intersection of both communities.


Improving Lossless Compression Rates via Monte Carlo Bits-Back Coding

arXiv.org Artificial Intelligence

Latent variable models have been successfully applied in lossless compression with the bits-back coding algorithm. However, bits-back suffers from an increase in the bitrate equal to the KL divergence between the approximate posterior and the true posterior. In this paper, we show how to remove this gap asymptotically by deriving bits-back coding algorithms from tighter variational bounds. The key idea is to exploit extended space representations of Monte Carlo estimators of the marginal likelihood. Naively applied, our schemes would require more initial bits than the standard bits-back coder, but we show how to drastically reduce this additional cost with couplings in the latent space. When parallel architectures can be exploited, our coders can achieve better rates than bits-back with little additional cost. We demonstrate improved lossless compression rates in a variety of settings, including entropy coding for lossy compression.


Comparative Fault Location Estimation by Using Image Processing in Mixed Transmission Lines

arXiv.org Artificial Intelligence

The distance protection relays are used to determine the impedance based fault location according to the current and voltage magnitudes in the transmission lines. However, the fault location cannot be correctly detected in mixed transmission lines due to different characteristic impedance per unit length because the characteristic impedance of high voltage cable line is significantly different from overhead line. Thus, determinations of the fault section and location with the distance protection relays are difficult in the mixed transmission lines. In this study, 154 kV overhead transmission line and underground cable line are examined as the mixed transmission line for the distance protection relays. Phase to ground faults are created in the mixed transmission line. overhead line section and underground cable section are simulated by using PSCAD-EMTDC.The short circuit fault images are generated in the distance protection relay for the overhead transmission line and underground cable transmission line faults. The images include the R-X impedance diagram of the fault, and the R-X impedance diagram have been detected by applying image processing steps. Artificial neural network (ANN) and the regression methods are used for prediction of the fault location, and the results of image processing are used as the input parameters for the training process of ANN and the regression methods. The results of ANN and regression methods are compared to select the most suitable method at the end of this study for forecasting of the fault location in transmission lines.


LogME: Practical Assessment of Pre-trained Models for Transfer Learning

arXiv.org Artificial Intelligence

This paper studies task adaptive pre-trained model selection, an \emph{underexplored} problem of assessing pre-trained models so that models suitable for the task can be selected from the model zoo without fine-tuning. A pilot work~\cite{nguyen_leep:_2020} addressed the problem in transferring supervised pre-trained models to classification tasks, but it cannot handle emerging unsupervised pre-trained models or regression tasks. In pursuit of a practical assessment method, we propose to estimate the maximum evidence (marginalized likelihood) of labels given features extracted by pre-trained models. The maximum evidence is \emph{less prone to over-fitting} than the likelihood, and its \emph{expensive computation can be dramatically reduced} by our carefully designed algorithm. The Logarithm of Maximum Evidence (LogME) can be used to assess pre-trained models for transfer learning: a pre-trained model with high LogME is likely to have good transfer performance. LogME is fast, accurate, and general, characterizing it as \emph{the first practical assessment method for transfer learning}. Compared to brute-force fine-tuning, LogME brings over $3000\times$ speedup in wall-clock time. It outperforms prior methods by a large margin in their setting and is applicable to new settings that prior methods cannot deal with. It is general enough to diverse pre-trained models (supervised pre-trained and unsupervised pre-trained), downstream tasks (classification and regression), and modalities (vision and language). Code is at \url{https://github.com/thuml/LogME}.


A Relational Tsetlin Machine with Applications to Natural Language Understanding

arXiv.org Artificial Intelligence

TMs are a pattern recognition approach that uses finite state machines for learning and propositional logic to represent patterns. In addition to being natively interpretable, they have provided competitive accuracy for various tasks. In this paper, we increase the computing power of TMs by proposing a first-order logic-based framework with Herbrand semantics. The resulting TM is relational and can take advantage of logical structures appearing in natural language, to learn rules that represent how actions and consequences are related in the real world. The outcome is a logic program of Horn clauses, bringing in a structured view of unstructured data. In closed-domain question-answering, the first-order representation produces 10x more compact KBs, along with an increase in answering accuracy from 94.83% to 99.48%. The approach is further robust towards erroneous, missing, and superfluous information, distilling the aspects of a text that are important for real-world understanding.


Shapley values for feature selection: The good, the bad, and the axioms

arXiv.org Artificial Intelligence

The Shapley value has become popular in the Explainable AI (XAI) literature, thanks, to a large extent, to a solid theoretical foundation, including four "favourable and fair" axioms for attribution in transferable utility games. The Shapley value is provably the only solution concept satisfying these axioms. In this paper, we introduce the Shapley value and draw attention to its recent uses as a feature selection tool. We call into question this use of the Shapley value, using simple, abstract "toy" counterexamples to illustrate that the axioms may work against the goals of feature selection. From this, we develop a number of insights that are then investigated in concrete simulation settings, with a variety of Shapley value formulations, including SHapley Additive exPlanations (SHAP) and Shapley Additive Global importancE (SAGE).


Linear unit-tests for invariance discovery

arXiv.org Artificial Intelligence

There is an increasing interest in algorithms to learn invariant correlations across training environments. A big share of the current proposals find theoretical support in the causality literature but, how useful are they in practice? The purpose of this note is to propose six linear low-dimensional problems --"unit tests"-- to evaluate different types of out-of-distribution generalization in a precise manner. Following initial experiments, none of the three recently proposed alternatives passes all tests.


BayesPerf: Minimizing Performance Monitoring Errors Using Bayesian Statistics

arXiv.org Artificial Intelligence

Hardware performance counters (HPCs) that measure low-level architectural and microarchitectural events provide dynamic contextual information about the state of the system. However, HPC measurements are error-prone due to non determinism (e.g., undercounting due to event multiplexing, or OS interrupt-handling behaviors). In this paper, we present BayesPerf, a system for quantifying uncertainty in HPC measurements by using a domain-driven Bayesian model that captures microarchitectural relationships between HPCs to jointly infer their values as probability distributions. We provide the design and implementation of an accelerator that allows for low-latency and low-power inference of the BayesPerf model for x86 and ppc64 CPUs. BayesPerf reduces the average error in HPC measurements from 40.1% to 7.6% when events are being multiplexed. The value of BayesPerf in real-time decision-making is illustrated with a simple example of scheduling of PCIe transfers.


Logistic Regression in SPSS for Social Science Research

#artificialintelligence

Logistic Regression in SPSS for Social Science Research Complete step by step guide on logistic regression in SPSS including interpretation and visualization New What you'll learn Social research with Logistic Regression in SPSS: A Complete Guide for the Social Sciences The only course on Udemy that shows you how to perform, interpret and visualize logistic regression in SPSS, using a real world example, using the quantitative research process. Follow along with me as I talk you through everything you need to know to become confident in using regression analysis in your quantitative research report, dissertation or thesis. Perfect for those studying social science subjects or want to increase their statistical confidence and literacy. Don't fall for other courses that are over-technical, math's based and heavy on statistics! This course cuts all that out and explains in a way that is easy to understand! Course outcomes On completion of the course you will fully understand: Logistics regression is a statistical model that is used to predict the probability of a certain outcome or event occurring, when that outcome or event is binary (such as pass/fail, true/false, healthy/sick).