Goto

Collaborating Authors

 Statistical Learning


Variational Interpretable Learning from Multi-view Data

arXiv.org Machine Learning

The main idea of canonical correlation analysis (CCA) is to map different views onto a common latent space with maximum correlation. We propose a deep interpretable variational canonical correlation analysis (DICCA) for multi-view learning. The developed model extends the existing latent variable model for linear CCA to nonlinear models through the use of deep generative networks. DICCA is designed to disentangle both the shared and view-specific variations for multi-view data. To further make the model more interpretable, we place a sparsity-inducing prior on the latent weight with a structured variational autoencoder that is comprised of view-specific generators. Empirical results on real-world datasets show that our methods are competitive across domains.


PUMA: Performance Unchanged Model Augmentation for Training Data Removal

arXiv.org Machine Learning

Preserving the performance of a trained model while removing unique characteristics of marked training data points is challenging. Recent research usually suggests retraining a model from scratch with remaining training data or refining the model by reverting the model optimization on the marked data points. Unfortunately, aside from their computational inefficiency, those approaches inevitably hurt the resulting model's generalization ability since they remove not only unique characteristics but also discard shared (and possibly contributive) information. To address the performance degradation problem, this paper presents a novel approach called Performance Unchanged Model Augmentation~(PUMA). The proposed PUMA framework explicitly models the influence of each training data point on the model's generalization ability with respect to various performance criteria. It then complements the negative impact of removing marked data by reweighting the remaining data optimally. To demonstrate the effectiveness of the PUMA framework, we compared it with multiple state-of-the-art data removal techniques in the experiments, where we show the PUMA can effectively and efficiently remove the unique characteristics of marked training data without retraining the model that can 1) fool a membership attack, and 2) resist performance degradation. In addition, as PUMA estimates the data importance during its operation, we show it could serve to debug mislabelled data points more efficiently than existing approaches.


A Unifying Framework for Some Directed Distances in Statistics

arXiv.org Machine Learning

Density-based directed distances -- particularly known as divergences -- between probability distributions are widely used in statistics as well as in the adjacent research fields of information theory, artificial intelligence and machine learning. Prominent examples are the Kullback-Leibler information distance (relative entropy) which e.g. is closely connected to the omnipresent maximum likelihood estimation method, and Pearson's chisquare-distance which e.g. is used for the celebrated chisquare goodness-of-fit test. Another line of statistical inference is built upon distribution-function-based divergences such as e.g. the prominent (weighted versions of) Cramer-von Mises test statistics respectively Anderson-Darling test statistics which are frequently applied for goodness-of-fit investigations; some more recent methods deal with (other kinds of) cumulative paired divergences and closely related concepts. In this paper, we provide a general framework which covers in particular both the above-mentioned density-based and distribution-function-based divergence approaches; the dissimilarity of quantiles respectively of other statistical functionals will be included as well. From this framework, we structurally extract numerous classical and also state-of-the-art (including new) procedures. Furthermore, we deduce new concepts of dependence between random variables, as alternatives to the celebrated mutual information. Some variational representations are discussed, too.


Neural Score Matching for High-Dimensional Causal Inference

arXiv.org Machine Learning

Traditional methods for matching in causal inference are impractical for high-dimensional datasets. They suffer from the curse of dimensionality: exact matching and coarsened exact matching find exponentially fewer matches as the input dimension grows, and propensity score matching may match highly unrelated units together. To overcome this problem, we develop theoretical results which motivate the use of neural networks to obtain non-trivial, multivariate balancing scores of a chosen level of coarseness, in contrast to the classical, scalar propensity score. We leverage these balancing scores to perform matching for high-dimensional causal inference and call this procedure neural score matching. We show that our method is competitive against other matching approaches on semi-synthetic high-dimensional datasets, both in terms of treatment effect estimation and reducing imbalance.


Essential list of useful R packages for data scientists

#artificialintelligence

I have written couple of blog posts on R packages (here here) and this blog post is sort of a preset of all the most needed packages for data science, statistical usage and every-day usage with R. Many useful functions are available in many different R packages, many of the same functionalities also in different packages, so it all boils down to user preferences and work, that one decides to use particular package. From the perspective of a statistician and data scientist, I will cover the essential and major packages in sections. And by no means, this is not a definite list, and only a personal preference. Loading and read data into R environment is most likely one of the first steps if not the most important.


Project 8 Part 1: Logistic Regression - Python

#artificialintelligence

Welcome Hi again, hi again! If you've been catching up with my blog, thanks for your continuous support If you're new here, thank you for giving my blog a chance Since I started learning R, I've thought about making code comparisons between Python and R. Concidentally, I've also started learning machine learning so I thought... why not try and compare machine learning codes between Python and R! So far, I've learned how to build logistic regression models using Python and R. Project 8 is divided into parts 1 and 2 where the codes using Python and R will be described respectively. I will be using the Iris dataset to demonstrate how the codes work If you're someone who requires assistive software to read, I suggest downloading the PDF documents to read the codes. Python - Jupyter Notebook For this project, I built a logistic regression model using sklearn. For starters, the packages I used were Pandas, Numpy, Scipy, Sklearn, and matplotlib.


R Programming: Selection of variables

#artificialintelligence

The all-possible-regressions procedure considers all possible subsets of the pool of potential explanatory variables Xi (with i 1, 2, โ€ฆ, m). It then identifies a small group of regression models which are "good" according to a specified criterion. A detailed examination of these models can lead to the selection of the final model. If there are m candidate explanatory variables: 2 m regressions for all possible subsets (e.g. if m 10, then there are 1024 possible regression models) The function leaps() (from package leaps) performs an exhaustive search for the best subsets of the explanatory variables for predicting the response variable in linear regression. This gave us a little idea but still, we are not sure how many parameters to be used.


Hyper Parameter Tuning with Uninformed and Informed Search

#artificialintelligence

Hyperparameters are those parameters in Machine learning algorithms that are used to control the learning process of algorithms. Hyperparameter tuning is the process of finding the best hyperparameters which help us to build more accurate machine learning models. Note: There is a difference between Model Parameters and Hyper Parameters. Model parameters are learned from data e.g. Slope and intercept in Linear Regression models, and Hyperparameters are those which we set such as L1 or L2 Regularization in Regression Model.


Rectified Max-Value Entropy Search for Bayesian Optimization

arXiv.org Machine Learning

Although the existing max-value entropy search (MES) is based on the widely celebrated notion of mutual information, its empirical performance can suffer due to two misconceptions whose implications on the exploration-exploitation trade-off are investigated in this paper. These issues are essential in the development of future acquisition functions and the improvement of the existing ones as they encourage an accurate measure of the mutual information such as the rectified MES (RMES) acquisition function we develop in this work. Unlike the evaluation of MES, we derive a closed-form probability density for the observation conditioned on the max-value and employ stochastic gradient ascent with reparameterization to efficiently optimize RMES. As a result of a more principled acquisition function, RMES shows a consistent improvement over MES in several synthetic function benchmarks and real-world optimization problems.


Survey and Evaluation of Causal Discovery Methods for Time Series

Journal of Artificial Intelligence Research

We introduce in this survey the major concepts, models, and algorithms proposed so far to infer causal relations from observational time series, a task usually referred to as causal discovery in time series. To do so, after a description of the underlying concepts and modelling assumptions, we present different methods according to the family of approaches they belong to: Granger causality, constraint-based approaches, noise-based approaches, score-based approaches, logic-based approaches, topology-based approaches, and difference-based approaches. We then evaluate several representative methods to illustrate the behaviour of different families of approaches. This illustration is conducted on both artificial and real datasets, with different characteristics. The main conclusions one can draw from this survey is that causal discovery in times series is an active research field in which new methods (in every family of approaches) are regularly proposed, and that no family or method stands out in all situations. Indeed, they all rely on assumptions that may or may not be appropriate for a particular dataset.