Binary geospatial data is commonly analyzed with generalized linear mixed models, specified with a linear fixed covariate effect and a Gaussian Process (GP)-distributed spatial random effect, relating to the response via a link function. The assumption of linear covariate effects is severely restrictive. Random Forests (RF) are increasingly being used for non-linear modeling of spatial data, but current extensions of RF for binary spatial data depart the mixed model setup, relinquishing inference on the fixed effects and other advantages of using GP. We propose RF-GP, using Random Forests for estimating the non-linear covariate effect and Gaussian Processes for modeling the spatial random effects directly within the generalized mixed model framework. We observe and exploit equivalence of Gini impurity measure and least squares loss to propose an extension of RF for binary data that accounts for the spatial dependence. We then propose a novel link inversion algorithm that leverages the properties of GP to estimate the covariate effects and offer spatial predictions. RF-GP outperforms existing RF methods for estimation and prediction in both simulated and real-world data. We establish consistency of RF-GP for a general class of $\beta$-mixing binary processes that includes common choices like spatial Mat\'ern GP and autoregressive processes.

Tree-based supervised learning algorithms, such as the Classification and Regression Tree (CART) (Breiman et al., 1984), Random Forests (Breiman, 2001), and XGBoost (Chen and Guestrin, 2016) are popular in practice due to their ability to learn complex nonlinear functions efficiently. Bayesian Additive Regression Trees (BART, Chipman et al. (2010)) is the most popular model-based regression tree method; it has been demonstrated empirically to provide accurate out-of-sample prediction (without covariate shift), and its Bayesian uncertainty intervals often out-perform alternatives in terms of frequentist coverage (see Chipman et al. (2010); Kapelner and Bleich (2013)). XBART (He and Hahn, 2021) is a stochastic tree ensemble method that can be used to approximate BART models in a fraction of the run-time. Throughout the paper, we will refer to BART models but will use the XBART fitting algorithm. While tree-based methods frequently provide accurate out-of-sample predictions, their ability to extrapolate is fundamentally limited by their intrinsic, piecewise constant structure.

Here's a new title that is a "must have" for any data scientist who uses the R language. It's a wonderful learning resource for tree-based techniques in statistical learning, one that's become my go-to text when I find the need to do a deep dive into various ML topic areas for my work. The methods discussed represent the cornerstone for using tabular data sets for making predictions using decision trees, ensemble methods like random forest, and of course the industry's darling gradient boosting machines (GBM). Algorithms like XGBoost are king of the hill for solving problems involving tabular data. A number of timely and somewhat high-profile benchmarks show that this class of algorithm beats deep learning algorithms for many problem domains.

Gradient boosting machines (GBMs) based on decision trees consistently demonstrate state-of-the-art results on regression and classification tasks with tabular data, often outperforming deep neural networks. However, these models do not provide well-calibrated predictive uncertainties, which prevents their use for decision making in high-risk applications. The Bayesian treatment is known to improve predictive uncertainty calibration, but previously proposed Bayesian GBM methods are either computationally expensive, or resort to crude approximations. Variational inference is often used to implement Bayesian neural networks, but is difficult to apply to GBMs, because the decision trees used as weak learners are non-differentiable. In this paper, we propose to implement Bayesian GBMs using variational inference with soft decision trees, a fully differentiable alternative to standard decision trees introduced by Irsoy et al. Our experiments demonstrate that variational soft trees and variational soft GBMs provide useful uncertainty estimates, while retaining good predictive performance. The proposed models show higher test likelihoods when compared to the state-of-the-art Bayesian GBMs in 7/10 tabular regression datasets and improved out-of-distribution detection in 5/10 datasets.

Vehicle insurance claims size prediction needs methods to efficiently handle these claims. Machine learning (ML) is one of the methods that solve this problem. Tree-based ensemble learning algorithms are highly effective and widely used ML methods. This study considers how vehicle insurance providers incorporate ML methods in their companies and explores how the models can be applied to insurance big data. We utilize various tree-based ML methods, such as bagging, random forest, and gradient boosting, to determine the relative importance of predictors in predicting claims size and to explore the relationships between claims size and predictors. Furthermore, we evaluate and compare these models' performances. The results show that tree-based ensemble methods are better than the classical least square method. Keywords: claims size prediction; machine learning; tree-based ensemble methods; vehicle insurance.

The emergence of Quantum Machine Learning (QML) to enhance traditional classical learning methods has seen various limitations to its realisation. There is therefore an imperative to develop quantum models with unique model hypotheses to attain expressional and computational advantage. In this work we extend the linear quantum support vector machine (QSVM) with kernel function computed through quantum kernel estimation (QKE), to form a decision tree classifier constructed from a decision directed acyclic graph of QSVM nodes - the ensemble of which we term the quantum random forest (QRF). To limit overfitting, we further extend the model to employ a low-rank Nystr\"{o}m approximation to the kernel matrix. We provide generalisation error bounds on the model and theoretical guarantees to limit errors due to finite sampling on the Nystr\"{o}m-QKE strategy. In doing so, we show that we can achieve lower sampling complexity when compared to QKE. We numerically illustrate the effect of varying model hyperparameters and finally demonstrate that the QRF is able obtain superior performance over QSVMs, while also requiring fewer kernel estimations.

Port scanning is the process of attempting to connect to various network ports on a computing endpoint to determine which ports are open and which services are running on them. It is a common method used by hackers to identify vulnerabilities in a network or system. By determining which ports are open, an attacker can identify which services and applications are running on a device and potentially exploit any known vulnerabilities in those services. Consequently, it is important to detect port scanning because it is often the first step in a cyber attack. By identifying port scanning attempts, cybersecurity professionals can take proactive measures to protect the systems and networks before an attacker has a chance to exploit any vulnerabilities. Against this background, researchers have worked for over a decade to develop robust methods to detect port scanning. One such method revealed by a recent systematic review is the random forest supervised machine learning algorithm. The review revealed six existing studies using random forest since 2021. Unfortunately, those studies each exhibit different results, do not all use the same training and testing dataset, and only two include source code. Accordingly, the goal of this work was to reproduce the six random forest studies while addressing the apparent shortcomings. The outcomes are significant for researchers looking to explore random forest to detect port scanning and for practitioners interested in reliable technology to detect the early stages of cyber attack.

I often talk about explainable AI(XAI) methods and how they can be adapted to address a few pain points that prohibit companies from building and deploying AI solutions. You can check my blog if you need a quick refresher on XAI methods. One such XAI method is Decision Trees. They have gained significant traction historically because of their interpretability and simplicity. However, many think that decision trees cannot be accurate because they look simple, and greedy algorithms like C4.5 and CART don't optimize them well.

Random forests use an ensemble learning method for classification or regression. A random forest classifier is used to solve classification problems. When we train a random forest with training data, it generates several decision trees. And then, when input features are provided, the random forest selects the class that is selected by most of the trees in the random forest. In our previous articles, we discussed classification trees and regression trees.

An evident challenge ahead for the integrated circuit (IC) industry in the nanometer regime is the investigation and development of methods that can reduce the design complexity ensuing from growing process variations and curtail the turnaround time of chip manufacturing. Conventional methodologies employed for such tasks are largely manual; thus, time-consuming and resource-intensive. In contrast, the unique learning strategies of artificial intelligence (AI) provide numerous exciting automated approaches for handling complex and data-intensive tasks in very-large-scale integration (VLSI) design and testing. Employing AI and machine learning (ML) algorithms in VLSI design and manufacturing reduces the time and effort for understanding and processing the data within and across different abstraction levels via automated learning algorithms. It, in turn, improves the IC yield and reduces the manufacturing turnaround time. This paper thoroughly reviews the AI/ML automated approaches introduced in the past towards VLSI design and manufacturing. Moreover, we discuss the scope of AI/ML applications in the future at various abstraction levels to revolutionize the field of VLSI design, aiming for high-speed, highly intelligent, and efficient implementations.