Performance Analysis
Intuition behind Bias-Variance trade-off, Lasso and Ridge Regression
We can see that Ridge and Lasso is performing far better than Linear Regression when the correlation exists in the dataset. We can tune our penalty parameter further and try to find best value of RMSE. Here, 0.01 is the best value I got for lambda. So, we can use these regression methods when the variables are highly correlated. Hope this article was useful in understanding Bias-Variance trade-off, Lasso and Ridge Regression. Please feel free to comment, give feedback and share this article if you found it useful. You can find the original article on my blog here.
Automated Interpretation of Blood Culture Gram Stains using a Deep Convolutional Neural Network
Microscopic interpretation of stained smears is one of the most operator-dependent and time intensive activities in the clinical microbiology laboratory. Here, we investigated application of an automated image acquisition and convolutional neural network (CNN)-based approach for automated Gram stain classification. Using an automated microscopy platform, uncoverslipped slides were scanned with a 40x dry objective, generating images of sufficient resolution for interpretation. We collected 25,488 images from positive blood culture Gram stains prepared during routine clinical workup. These images were used to generate 100,213 crops containing Gram-positive cocci in clusters, Gram-positive cocci in chains/pairs, Gram-negative rods, or background (no cells).
Joint mean and covariance estimation with unreplicated matrix-variate data
Hornstein, Michael, Fan, Roger, Shedden, Kerby, Zhou, Shuheng
It has been proposed that complex populations, such as those that arise in genomics studies, may exhibit dependencies among observations as well as among variables. This gives rise to the challenging problem of analyzing unreplicated high-dimensional data with unknown mean and dependence structures. Matrix-variate approaches that impose various forms of (inverse) covariance sparsity allow flexible dependence structures to be estimated, but cannot directly be applied when the mean and covariance matrices are estimated jointly. We present a practical method utilizing generalized least squares and penalized (inverse) covariance estimation to address this challenge. We establish consistency and obtain rates of convergence for estimating the mean parameters and covariance matrices. The advantages of our approaches are: (i) dependence graphs and covariance structures can be estimated in the presence of unknown mean structure, (ii) the mean structure becomes more efficiently estimated when accounting for the dependence structure among observations; and (iii) inferences about the mean parameters become correctly calibrated. We use simulation studies and analysis of genomic data from a twin study of ulcerative colitis to illustrate the statistical convergence and the performance of our methods in practical settings. Several lines of evidence show that the test statistics for differential gene expression produced by our methods are correctly calibrated and improve power over conventional methods.
Social Media Analysis based on Semanticity of Streaming and Batch Data
Languages shared by people differ in different regions based on their accents, pronunciation and word usages. In this era sharing of language takes place mainly through social media and blogs. Every second swing of such a micro posts exist which induces the need of processing those micro posts, in-order to extract knowledge out of it. Knowledge extraction differs with respect to the application in which the research on cognitive science fed the necessities for the same. This work further moves forward such a research by extracting semantic information of streaming and batch data in applications like Named Entity Recognition and Author Profiling. In the case of Named Entity Recognition context of a single micro post has been utilized and context that lies in the pool of micro posts were utilized to identify the sociolect aspects of the author of those micro posts. In this work Conditional Random Field has been utilized to do the entity recognition and a novel approach has been proposed to find the sociolect aspects of the author (Gender, Age group).
Learning Curves for Machine Learning
When building machine learning models, we want to keep error as low as possible. Two major sources of error are bias and variance. If we managed to reduce these two, then we could build more accurate models. But how do we diagnose bias and variance in the first place? And what actions should we take once we've detected something? In this post, we'll learn how to answer both these questions using learning curves. We'll work with a real world data set and try to predict the electrical energy output of a power plant. Some familiarity with scikit-learn and machine learning theory is assumed. If you don't frown when I say cross-validation or supervised learning, then you're good to go. If you're new to machine learning and have never tried scikit, a good place to start is this blog post. We begin with a brief introduction to bias and variance.
AI and Machine Learning in Cyber Security – Towards Data Science
Zen monks have been using a tool called a'koan' for hundreds of years to assist them in reaching enlightenment. These koans are like riddles or stories that can only be solved by letting go of ones narrowing believes and stories about how things should be. Zen students sit in silent meditation and observe how the koan is working on them, slowly transforming their way of looking at the world and revealing a tiny piece of the path to nirvana, that place of no suffering. You might wonder what that has to do with cyber security. With the increased popularity of deep learning and the omni presence of the term artificial intelligence (AI), a lot of security practitioners are tricked into believing that these approaches are the magic silver bullet we have been waiting for to solve all of our cyber security challenges.
Why machine learning isn't a cure-all to improve security
Hospitals and other healthcare providers continue to be prime targets for hackers, and as providers increasingly depend on the constant flow of information through their systems, the potential negative effects of attacks loom larger in 2018. In addition to the substantial financial costs associated with cyberattacks, security breaches frequently disrupt critical medical services--a major problem when hospitals get attacked is that patient record systems can go down or become encrypted. When that happens, doctors are forced to revert to taking and circulating patient notes by hand. They may not be able to access important information regarding patient history, medications, test results and more. With the threat of and severity of attacks becoming more damaging than ever, healthcare organizations are increasingly looking for new security solutions that can better protect them.
Union of Intersections (UoI) for Interpretable Data Driven Discovery and Prediction
Bouchard, Kristofer, Bujan, Alejandro, Roosta-Khorasani, Farbod, Ubaru, Shashanka, Prabhat, Mr., Snijders, Antoine, Mao, Jian-Hua, Chang, Edward, Mahoney, Michael W., Bhattacharya, Sharmodeep
The increasing size and complexity of scientific data could dramatically enhance discovery and prediction for basic scientific applications, e.g., neuroscience, genetics, systems biology, etc. Realizing this potential, however, requires novel statistical analysis methods that are both interpretable and predictive. We introduce the Union of Intersections (UoI) method, a flexible, modular, and scalable framework for enhanced model selection and estimation. The method performs model selection and model estimation through intersection and union operations, respectively. We show that UoI can satisfy the bi-criteria of low-variance and nearly unbiased estimation of a small number of interpretable features, while maintaining high-quality prediction accuracy. We perform extensive numerical investigation to evaluate a UoI algorithm ($UoI_{Lasso}$) on synthetic and real data. In doing so, we demonstrate the extraction of interpretable functional networks from human electrophysiology recordings as well as the accurate prediction of phenotypes from genotype-phenotype data with reduced features. We also show (with the $UoI_{L1Logistic}$ and $UoI_{CUR}$ variants of the basic framework) improved prediction parsimony for classification and matrix factorization on several benchmark biomedical data sets. These results suggest that methods based on UoI framework could improve interpretation and prediction in data-driven discovery across scientific fields.
Efficient Approximation Algorithms for Strings Kernel Based Sequence Classification
Farhan, Muhammad, Tariq, Juvaria, Zaman, Arif, Shabbir, Mudassir, Khan, Imdad Ullah
Sequence classification algorithms, such as SVM, require a definition of distance (similarity) measure between two sequences. A commonly used notion of similarity is the number of matches between k-mers (k-length subsequences) in the two sequences. Extending this definition, by considering two k-mers to match if their distance is at most m, yields better classification performance. This, however, makes the problem computationally much more complex. Known algorithms to compute this similarity have computational complexity that render them applicable only for small values of k and m. In this work, we develop novel techniques to efficiently and accurately estimate the pairwise similarity score, which enables us to use much larger values of k and m, and get higher predictive accuracy. This opens up a broad avenue of applying this classification approach to audio, images, and text sequences. Our algorithm achieves excellent approximation performance with theoretical guarantees. In the process we solve an open combinatorial problem, which was posed as a major hindrance to the scalability of existing solutions. We give analytical bounds on quality and runtime of our algorithm and report its empirical performance on real world biological and music sequences datasets.