Statistical Learning
Machine Learning K-Nearest Neighbors (KNN) Algorithm In Python
Now, let us understand the implementation of K-Nearest Neighbors in Python in creating a trading strategy. We will start by importing the necessary libraries. We will import the pandas libraries to use the features of its powerful dataframe. We will import the numpy libraries for scientific calculation. Next, we will import the matplotlib.pyplot
Multivariate normal mixture modeling, clustering and classification with the rebmix package
The rebmix package provides R functions for random univariate and multivariate finite mixture model generation, estimation, clustering and classification. The paper is focused on multivariate normal mixture models with unrestricted variance-covariance matrices. The objective is to show how to generate datasets for a known number of components, numbers of observations and component parameters, how to estimate the number of components, component weights and component parameters and how to predict cluster and class membership based upon a model trained by the REBMIX algorithm. The accompanying plotting, bootstrapping and other features of the package are dealt with, too. For demonstration purpose a multivariate normal dataset with unrestricted variance-covariance matrices is studied.
Time Series Segmentation through Automatic Feature Learning
Lee, Wei-Han, Ortiz, Jorge, Ko, Bongjun, Lee, Ruby
Internet of things (IoT) applications have become increasingly popular in recent years, with applications ranging from building energy monitoring to personal health tracking and activity recognition. In order to leverage these data, automatic knowledge extraction - whereby we map from observations to interpretable states and transitions - must be done at scale. As such, we have seen many recent IoT data sets include annotations with a human expert specifying states, recorded as a set of boundaries and associated labels in a data sequence. These data can be used to build automatic labeling algorithms that produce labels as an expert would. Here, we refer to human-specified boundaries as breakpoints. Traditional changepoint detection methods only look for statistically-detectable boundaries that are defined as abrupt variations in the generative parameters of a data sequence. However, we observe that breakpoints occur on more subtle boundaries that are non-trivial to detect with these statistical methods. In this work, we propose a new unsupervised approach, based on deep learning, that outperforms existing techniques and learns the more subtle, breakpoint boundaries with a high accuracy. Through extensive experiments on various real-world data sets - including human-activity sensing data, speech signals, and electroencephalogram (EEG) activity traces - we demonstrate the effectiveness of our algorithm for practical applications. Furthermore, we show that our approach achieves significantly better performance than previous methods.
Elastic-net regularized High-dimensional Negative Binomial Regression: Consistency and Weak Signals Detection
We study sparse high-dimensional negative binomial regression problem for count data regression by showing non-asymptotic merits of the Elastic-net regularized estimator. With the KKT conditions, we derive two types of non-asymptotic oracle inequalities for the elastic net estimates of negative binomial regression by utilizing Compatibility factor and Stabil Condition, respectively. Based on oracle inequalities we proposed, we firstly show the sign consistency property of the Elastic-net estimators provided that the non-zero components in sparse true vector are large than a proper choice of the weakest signal detection threshold, and the second application is that we give an oracle inequality for bounding the grouping effect with high probability, thirdly, under some assumptions of design matrix, we can recover the true variable set with high probability if the weakest signal detection threshold is large than 3 times the value of turning parameter, at last, we briefly discuss the de-biased Elastic-net estimator.
Spoken English Intelligibility Remediation with PocketSphinx Alignment and Feature Extraction Improves Substantially over the State of the Art
Gao, Yuan, Srivastava, Brij Mohan Lal, Salsman, James
ABSTRACT We use automatic speech recognition to assess spoken English learner pronunciation based on the authentic intelligibility of the learners' spoken responses determined from support vector machine (SVM) classifier or deep learning neural network model predictions of transcription correctness. Using numeric features produced by PocketSphinx alignment mode and many recognition passes searching for the substitution and deletion of each expected phoneme and insertion of unexpected phonemes in sequence, the SVM models achieve 82% agreement with the accuracy of Amazon Mechanical Turk crowdworker transcriptions, up from 75% reported by multiple independent researchers. Using such features with SVM classifier probability prediction models can help computeraided pronunciation teaching (CAPT) systems provide intelligibility remediation. Index Terms-- phoneme alignment, pronunciation assessment, computer aided language learning, binary features 1. INTRODUCTION Authentic intelligibility, the ability of listeners to correctly transcribe recorded utterances, initially used for CAPT by [1] and [2], is a better measure of pronunciation assessment for spoken language learners compared to mispronunciations identified by expert pronunciation judges or panels of experts, because such mispronunciations are associated with only 16% of intelligibility problems, according to [3], who state: We investigated... which words are likely to be misrecognized and which words are likely to be marked as pronunciation errors. Words perceived as mispronounced remain intelligible in about half of all cases.
Underdamped Langevin MCMC: A non-asymptotic analysis
Cheng, Xiang, Chatterji, Niladri S., Bartlett, Peter L., Jordan, Michael I.
We study the underdamped Langevin diffusion when the log of the target distribution is smooth and strongly concave. We present a MCMC algorithm based on its discretization and show that it achieves $\varepsilon$ error (in 2-Wasserstein distance) in $\mathcal{O}(\sqrt{d}/\varepsilon)$ steps. This is a significant improvement over the best known rate for overdamped Langevin MCMC, which is $\mathcal{O}(d/\varepsilon^2)$ steps under the same smoothness/concavity assumptions. The underdamped Langevin MCMC scheme can be viewed as a version of Hamiltonian Monte Carlo (HMC) which has been observed to outperform overdamped Langevin MCMC methods in a number of application areas. We provide quantitative rates that support this empirical wisdom.
Beyond Volume: The Impact of Complex Healthcare Data on the Machine Learning Pipeline
Feldman, Keith, Faust, Louis, Wu, Xian, Huang, Chao, Chawla, Nitesh V.
From medical charts to national census, healthcare has traditionally operated under a paper-based paradigm. However, the past decade has marked a long and arduous transformation bringing healthcare into the digital age. Ranging from electronic health records, to digitized imaging and laboratory reports, to public health datasets, today, healthcare now generates an incredible amount of digital information. Such a wealth of data presents an exciting opportunity for integrated machine learning solutions to address problems across multiple facets of healthcare practice and administration. Unfortunately, the ability to derive accurate and informative insights requires more than the ability to execute machine learning models. Rather, a deeper understanding of the data on which the models are run is imperative for their success. While a significant effort has been undertaken to develop models able to process the volume of data obtained during the analysis of millions of digitalized patient records, it is important to remember that volume represents only one aspect of the data. In fact, drawing on data from an increasingly diverse set of sources, healthcare data presents an incredibly complex set of attributes that must be accounted for throughout the machine learning pipeline. This chapter focuses on highlighting such challenges, and is broken down into three distinct components, each representing a phase of the pipeline. We begin with attributes of the data accounted for during preprocessing, then move to considerations during model building, and end with challenges to the interpretation of model output. For each component, we present a discussion around data as it relates to the healthcare domain and offer insight into the challenges each may impose on the efficiency of machine learning techniques.
Which Machine Learning Algo will continue to be in use in year 2118?
So what were the answers popping in your head? Random forest, SVM, K means, Knn or even Deep Learning and its variants? Now some of you might laugh and say how on earth can you predict so far ahead, predicting things 100 yrs into future is crazy. Well the answer is Lindy effect. Yes, the heuristic I am using to predict this is Lindy Effect.
Perform Multiple Linear Regression for Time Series data?
I am provided with 3 years worth of Sales data (broken down by month) along with data for multiple potential independent variables like Ad Spend (broken down by TV and Digital), Population Increase, Consumer purchase index. I am required to a) Forecast Sales data and B) find the effect of these dependent variables on Sales and what is the optimal mix of Ad spend (TV vs Digital) for Sales. I wish to run an equivalent of multiple linear regression in Python but for Time Series data. All the examples that I have read for Time Series focus on 1 independent variable. How can I incorporate multiple independent variables into a linear regression model for Time Series?