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 Regression


User Modelling for Avoiding Overfitting in Interactive Knowledge Elicitation for Prediction

arXiv.org Machine Learning

In human-in-the-loop machine learning, the user provides information beyond that in the training data. Many algorithms and user interfaces have been designed to optimize and facilitate this human--machine interaction; however, fewer studies have addressed the potential defects the designs can cause. Effective interaction often requires exposing the user to the training data or its statistics. The design of the system is then critical, as this can lead to double use of data and overfitting, if the user reinforces noisy patterns in the data. We propose a user modelling methodology, by assuming simple rational behaviour, to correct the problem. We show, in a user study with 48 participants, that the method improves predictive performance in a sparse linear regression sentiment analysis task, where graded user knowledge on feature relevance is elicited. We believe that the key idea of inferring user knowledge with probabilistic user models has general applicability in guarding against overfitting and improving interactive machine learning.


Automated versus do-it-yourself methods for causal inference: Lessons learned from a data analysis competition

arXiv.org Machine Learning

Statisticians have made great progress in creating methods that reduce our reliance on parametric assumptions. However this explosion in research has resulted in a breadth of inferential strategies that both create opportunities for more reliable inference as well as complicate the choices that an applied researcher has to make and defend. Relatedly, researchers advocating for new methods typically compare their method to at best 2 or 3 other causal inference strategies and test using simulations that may or may not be designed to equally tease out flaws in all the competing methods. The causal inference data analysis challenge, "Is Your SATT Where It's At?", launched as part of the 2016 Atlantic Causal Inference Conference, sought to make progress with respect to both of these issues. The researchers creating the data testing grounds were distinct from the researchers submitting methods whose efficacy would be evaluated. Results from 30 competitors across the two versions of the competition (black box algorithms and do-it-yourself analyses) are presented along with post-hoc analyses that reveal information about the characteristics of causal inference strategies and settings that affect performance. The most consistent conclusion was that methods that flexibly model the response surface perform better overall than methods that fail to do so. Finally new methods are proposed that combine features of several of the top-performing submitted methods.


High-dimensional classification by sparse logistic regression

arXiv.org Machine Learning

We consider high-dimensional binary classification by sparse logistic regression. We propose a model/feature selection procedure based on penalized maximum likelihood with a complexity penalty on the model size and derive the non-asymptotic bounds for the resulting misclassification excess risk. The bounds can be reduced under the additional low-noise condition. The proposed complexity penalty is remarkably related to the VC-dimension of a set of sparse linear classifiers. Implementation of any complexity penalty-based criterion, however, requires a combinatorial search over all possible models. To find a model selection procedure computationally feasible for high-dimensional data, we extend the Slope estimator for logistic regression and show that under an additional weighted restricted eigenvalue condition it is rate-optimal in the minimax sense.


Revisiting differentially private linear regression: optimal and adaptive prediction & estimation in unbounded domain

arXiv.org Machine Learning

Linear regression is one of the oldest tools for data analysis (Galton, 1886) and it remains one of the most commonly-used as of today (Draper & Smith, 2014), especially in social sciences (Agresti & Finlay, 1997), econometics (Greene, 2003) and medical research (Armitage et al., 2008). Moreover, many nonlinear models are either intrinsically linear in certain function spaces, e.g., kernels methods, dynamical systems, or can be reduced to solving a sequence of linear regressions, e.g., iterative reweighted least square for generalized Linear models, gradient boosting for additive models and so on (see Friedman et al., 2001, for a detailed review). In order to apply linear regression to sensitive data such as those in social sciences and medical studies, it is often needed to do so such that the privacy of individuals in the data set is protected. Differential privacy (Dwork et al., 2006b) is a commonly-accepted criterion that provides provable protection against identification and is resilient to arbitrary auxiliary information that might be available to attackers. In this paper, we focus on linear regression with (ษ›, ฮด)-differentially privacy (Dwork et al., 2006a).


Optimal Subsampling for Large Sample Logistic Regression

arXiv.org Machine Learning

For massive data, the family of subsampling algorithms is popular to downsize the data volume and reduce computational burden. Existing studies focus on approximating the ordinary least squares estimate in linear regression, where statistical leverage scores are often used to define subsampling probabilities. In this paper, we propose fast subsampling algorithms to efficiently approximate the maximum likelihood estimate in logistic regression. We first establish consistency and asymptotic normality of the estimator from a general subsampling algorithm, and then derive optimal subsampling probabilities that minimize the asymptotic mean squared error of the resultant estimator. An alternative minimization criterion is also proposed to further reduce the computational cost. The optimal subsampling probabilities depend on the full data estimate, so we develop a two-step algorithm to approximate the optimal subsampling procedure. This algorithm is computationally efficient and has a significant reduction in computing time compared to the full data approach. Consistency and asymptotic normality of the estimator from a two-step algorithm are also established. Synthetic and real data sets are used to evaluate the practical performance of the proposed method.


On Nonlinear Dimensionality Reduction, Linear Smoothing and Autoencoding

arXiv.org Machine Learning

We develop theory for nonlinear dimensionality reduction (NLDR). A number of NLDR methods have been developed, but there is limited understanding of how these methods work and the relationships between them. There is limited basis for using existing NLDR theory for deriving new algorithms. We provide a novel framework for analysis of NLDR via a connection to the statistical theory of linear smoothers. This allows us to both understand existing methods and derive new ones. We use this connection to smoothing to show that asymptotically, existing NLDR methods correspond to discrete approximations of the solutions of sets of differential equations given a boundary condition. In particular, we can characterize many existing methods in terms of just three limiting differential operators and boundary conditions. Our theory also provides a way to assert that one method is preferable to another; indeed, we show Local Tangent Space Alignment is superior within a class of methods that assume a global coordinate chart defines an isometric embedding of the manifold.


How to Solve Linear Regression Using Linear Algebra - Machine Learning Mastery

#artificialintelligence

This can be solved directly, although given the presence of the matrix inverse can be numerically challenging or unstable. In order to explore the matrix formulation of linear regression, let's first define a dataset as a context. We will use a simple 2D dataset where the data is easy to visualize as a scatter plot and models are easy to visualize as a line that attempts to fit the data points. The example below defines a 5 2 matrix dataset, splits it into X and y components, and plots the dataset as a scatter plot. Running the example first prints the defined dataset. A scatter plot of the dataset is then created showing that a straight line cannot fit this data exactly.


Linear Regression in Tensorflow

@machinelearnbot

Tensorflow is an open source machine learning (ML) library from Google. It has particularly became popular because of the support for Deep Learning. Apart from that it's highly scalable and can run on Android. The documentation is well maintained and several tutorials available for different expertise levels. To learn more about downloading and installing Tesnorflow, visit official website.


Data Science Simplified Part 7: Log-Log Regression Models

@machinelearnbot

The logarithm is an interesting character. Let us only understand its personality applicable for regression models. The fundamental property of a logarithm is its base. The typical base of the logarithm is 2, 10 or e. There is another common base for logarithms.


Artificial Intelligence vs Business Intelligence - Learn 6 Useful Comparison

#artificialintelligence

Business Intelligence is a technology that is used to gather, store, access and analyzes data to help business users in making better decisions, on the other hand, Artificial Intelligence is a way to make a computer, a computer-controlled robot, or a software that think intelligently like humans.Artificial Intelligence is based on the study that how human thinks, learn, decide and work in order to resolve an issue and then using the outcome of this study as a basis of developing intelligent software and systems. It starts from root node and explores neighbor nodes first and moves to the next level neighbor nodes.It provides the shortest path to the solution and can be implemented using FIFO This algorithm is implemented using LIFO(Last in first out)data structure.It creates nodes same as breadth-first search but it differs in only order.In each iteration, it stores the nodes from root to leaf and also it cannot check duplicate nodes. It makes predictions by using Bayes algorithm, which derives probability prediction from the underlying evidence, as observed in data. In this algorithm, sorting is done in increasing cost of the path to a node.It always expands the least cost node.This search is identical to the Breadth-first search if each transition has the same cost.It explores the path in the increasing order of cost. It implements logistic regression for classification of binary targets and linear regression for continuous targets.It supports confidence bounds for prediction probabilities and also supports confidence bounds for prediction. It performs the depth-first search at level-1 and starts over, then executes a complete depth-first search to level 2, and continues till it gets the solution.