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 Statistical Learning


Comparing Explanation Methods for Traditional Machine Learning Models Part 1: An Overview of Current Methods and Quantifying Their Disagreement

arXiv.org Artificial Intelligence

We demonstrate and visualize different explanation methods, how to interpret them, and provide a complete Python package (scikit-explain) to allow future researchers to explore these products. We also highlight the frequent disagreement between explanation methods for feature rankings and feature effects and provide practical advice for dealing with these disagreements. We used ML models developed for severe weather prediction and sub-freezing road surface temperature prediction to generalize the behavior of the different explanation methods. For feature rankings, there is substantially more agreement on the set of top features (e.g., on average, two methods agree on 6 of the top 10 features) than on specific rankings (on average, two methods only agree on the ranks of 2-3 features in the set of top 10 features). On the other hand, two feature effect curves from different methods are in high agreement as long as the phase space is well sampled. Finally, a lesser-known method, tree interpreter, was found comparable to SHAP for feature effects, and with the widespread use of random forests in geosciences and computational ease of tree interpreter, we recommend it be explored in future research.


What Has Been Enhanced in my Knowledge-Enhanced Language Model?

arXiv.org Artificial Intelligence

Pretrained language models (LMs) do not capture factual knowledge very well. This has led to the development of a number of knowledge integration (KI) methods which aim to incorporate external knowledge into pretrained LMs. Even though KI methods show some performance gains over vanilla LMs, the inner-workings of these methods are not well-understood. For instance, it is unclear how and what kind of knowledge is effectively integrated into these models and if such integration may lead to catastrophic forgetting of already learned knowledge. This paper revisits the KI process in these models with an information-theoretic view and shows that KI can be interpreted using a graph convolution operation. We propose a probe model called \textit{Graph Convolution Simulator} (GCS) for interpreting knowledge-enhanced LMs and exposing what kind of knowledge is integrated into these models. We conduct experiments to verify that our GCS can indeed be used to correctly interpret the KI process, and we use it to analyze two well-known knowledge-enhanced LMs: ERNIE and K-Adapter, and find that only a small amount of factual knowledge is integrated in them. We stratify knowledge in terms of various relation types and find that ERNIE and K-Adapter integrate different kinds of knowledge to different extent. Our analysis also shows that simply increasing the size of the KI corpus may not lead to better KI; fundamental advances may be needed.


Transfer Learning

#artificialintelligence

Machine Learning (ML) involves data analysis and enables the system to improve and learn from experience without explicit programming required constantly. There have been many ML approaches that came into existence constantly. Supervised learning was a game-changing approach that was adopted widely across many industries. However, a few limitations of supervised learning can be overcome with the onset of various other approaches. Transfer Learning is a method under research in Machine Learning that stores the knowledge obtained from solving one problem and uses it to solve problems that are different but related to the solved one. Since training a model takes more computational power, time, and data, Transfer Learning helps reduce the same while improving learning accuracy. The target learner learns from the model, which is already trained initially by using the stored knowledge.


4 Must-Know Machine Learning Algorithms

#artificialintelligence

One consequence of using this algorithm is that the results are often inconsistent. It is order-dependent, so any change to the order of an existing data set can affect its outcome. Moreover, it lacks a uniform effect and can only handle numerical data. Despite these limitations, K-Means is one of the best-performing machine learning algorithms. It is perfect for segmenting datasets and is trusted for its adaptability.


Time Series Analysis in Python - Data Analysis & Forecasting

#artificialintelligence

Welcome to the Python for Time Series - Data Analysis & Forecasting course. This course is built for students who wants to learn python applications for time series data sets. This course covers the usage of Python libraries on time series data. There will be both short lectures of statistics and Python fundamentals at the starting of the course in order to remembering the basics. Then the libraries of Python which is used for time series data will be covered.


200 Most Popular Machine Learning interview Questions and answers

#artificialintelligence

Machine Learning involves algorithms that learn from patterns of data and then apply it to decision making. Deep Learning, on the other hand, is able to learn through processing data on its own and is quite similar to the human brain where it identifies something, analyse it, and makes a decision.


Custom models with TensorFlow (Part-1)->Multi-output model

#artificialintelligence

Using the below source code we will specify the optimizer as stochastic gradient descent and will mention the learning rate as 0.001. After that, we will compile the model with loss functions for both outputs. Note: We can mention different loss functions for different outputs. In the same way, we can also mention different metrics for different outputs. Using the below syntax we will train the model for 500 epochs.


Virgo: Scalable Unsupervised Classification of Cosmological Shock Waves

arXiv.org Artificial Intelligence

Cosmological shock waves are essential to understanding the formation of cosmological structures. To study them, scientists run computationally expensive high-resolution 3D hydrodynamic simulations. Interpreting the simulation results is challenging because the resulting data sets are enormous, and the shock wave surfaces are hard to separate and classify due to their complex morphologies and multiple shock fronts intersecting. We introduce a novel pipeline, Virgo, combining physical motivation, scalability, and probabilistic robustness to tackle this unsolved unsupervised classification problem. To this end, we employ kernel principal component analysis with low-rank matrix approximations to denoise data sets of shocked particles and create labeled subsets. We perform supervised classification to recover full data resolution with stochastic variational deep kernel learning. We evaluate on three state-of-the-art data sets with varying complexity and achieve good results. The proposed pipeline runs automatically, has only a few hyperparameters, and performs well on all tested data sets. Our results are promising for large-scale applications, and we highlight now enabled future scientific work.


Data efficient surrogate modeling for engineering design: Ensemble-free batch mode deep active learning for regression

arXiv.org Artificial Intelligence

In a computer-aided engineering design optimization problem that involves notoriously complex and time-consuming simulator, the prevalent approach is to replace these simulations with a data-driven surrogate that approximates the simulator's behavior at a much cheaper cost. The main challenge in creating an inexpensive data-driven surrogate is the generation of a sheer number of data using these computationally expensive numerical simulations. In such cases, Active Learning (AL) methods have been used that attempt to learn an input--output behavior while labeling the fewest samples possible. The current trend in AL for a regression problem is dominated by the Bayesian framework that needs training an ensemble of learning models that makes surrogate training computationally tedious if the underlying learning model is Deep Neural Networks (DNNs). However, DNNs have an excellent capability to learn highly nonlinear and complex relationships even for a very high dimensional problem. To leverage the excellent learning capability of deep networks along with avoiding the computational complexity of the Bayesian paradigm, in this work we propose a simple and scalable approach for active learning that works in a student-teacher manner to train a surrogate model. By using this proposed approach, we are able to achieve the same level of surrogate accuracy as the other baselines like DBAL and Monte Carlo sampling with up to 40 % fewer samples. We empirically evaluated this method on multiple use cases including three different engineering design domains:finite element analysis, computational fluid dynamics, and propeller design.


Exploring Supervised Machine Learning for Multi-Phase Identification and Quantification from Powder X-Ray Diffraction Spectra

arXiv.org Artificial Intelligence

Powder X-ray diffraction analysis is a critical component of materials characterization methodologies. Discerning characteristic Bragg intensity peaks and assigning them to known crystalline phases is the first qualitative step of evaluating diffraction spectra. Subsequent to phase identification, Rietveld refinement may be employed to extract the abundance of quantitative, material-specific parameters hidden within powder data. These characterization procedures are yet time-consuming and inhibit efficiency in materials science workflows. The ever-increasing popularity and propulsion of data science techniques has provided an obvious solution on the course towards materials analysis automation. Deep learning has become a prime focus for predicting crystallographic parameters and features from X-ray spectra. However, the infeasibility of curating large, well-labelled experimental datasets means that one must resort to a large number of theoretic simulations for powder data augmentation to effectively train deep models. Herein, we are interested in conventional supervised learning algorithms in lieu of deep learning for multi-label crystalline phase identification and quantitative phase analysis for a biomedical application. First, models were trained using very limited experimental data. Further, we incorporated simulated XRD data to assess model generalizability as well as the efficacy of simulation-based training for predictive analysis in a real-world X-ray diffraction application.