Statistical Learning
Tackling System and Statistical Heterogeneity for Federated Learning with Adaptive Client Sampling
Luo, Bing, Xiao, Wenli, Wang, Shiqiang, Huang, Jianwei, Tassiulas, Leandros
Federated learning (FL) algorithms usually sample a fraction of clients in each round (partial participation) when the number of participants is large and the server's communication bandwidth is limited. Recent works on the convergence analysis of FL have focused on unbiased client sampling, e.g., sampling uniformly at random, which suffers from slow wall-clock time for convergence due to high degrees of system heterogeneity and statistical heterogeneity. This paper aims to design an adaptive client sampling algorithm that tackles both system and statistical heterogeneity to minimize the wall-clock convergence time. We obtain a new tractable convergence bound for FL algorithms with arbitrary client sampling probabilities. Based on the bound, we analytically establish the relationship between the total learning time and sampling probabilities, which results in a non-convex optimization problem for training time minimization. We design an efficient algorithm for learning the unknown parameters in the convergence bound and develop a low-complexity algorithm to approximately solve the non-convex problem. Experimental results from both hardware prototype and simulation demonstrate that our proposed sampling scheme significantly reduces the convergence time compared to several baseline sampling schemes. Notably, our scheme in hardware prototype spends 73% less time than the uniform sampling baseline for reaching the same target loss.
Toward Explainable AI for Regression Models
Letzgus, Simon, Wagner, Patrick, Lederer, Jonas, Samek, Wojciech, Mรผller, Klaus-Robert, Montavon, Gregoire
In addition to the impressive predictive power of machine learning (ML) models, more recently, explanation methods have emerged that enable an interpretation of complex non-linear learning models such as deep neural networks. Gaining a better understanding is especially important e.g. for safety-critical ML applications or medical diagnostics etc. While such Explainable AI (XAI) techniques have reached significant popularity for classifiers, so far little attention has been devoted to XAI for regression models (XAIR). In this review, we clarify the fundamental conceptual differences of XAI for regression and classification tasks, establish novel theoretical insights and analysis for XAIR, provide demonstrations of XAIR on genuine practical regression problems, and finally discuss the challenges remaining for the field.
Graph-based Ensemble Machine Learning for Student Performance Prediction
Wang, Yinkai, Ding, Aowei, Guan, Kaiyi, Wu, Shixi, Du, Yuanqi
Student performance prediction is a critical research problem to understand the students' needs, present proper learning opportunities/resources, and develop the teaching quality. However, traditional machine learning methods fail to produce stable and accurate prediction results. In this paper, we propose a graph-based ensemble machine learning method that aims to improve the stability of single machine learning methods via the consensus of multiple methods. To be specific, we leverage both supervised prediction methods and unsupervised clustering methods, build an iterative approach that propagates in a bipartite graph as well as converges to more stable and accurate prediction results. Extensive experiments demonstrate the effectiveness of our proposed method in predicting more accurate student performance. Specifically, our model outperforms the best traditional machine learning algorithms by up to 14.8% in prediction accuracy.
MultiPath++: Efficient Information Fusion and Trajectory Aggregation for Behavior Prediction
Varadarajan, Balakrishnan, Hefny, Ahmed, Srivastava, Avikalp, Refaat, Khaled S., Nayakanti, Nigamaa, Cornman, Andre, Chen, Kan, Douillard, Bertrand, Lam, Chi Pang, Anguelov, Dragomir, Sapp, Benjamin
Predicting the future behavior of road users is one of the most challenging and important problems in autonomous driving. Applying deep learning to this problem requires fusing heterogeneous world state in the form of rich perception signals and map information, and inferring highly multi-modal distributions over possible futures. In this paper, we present MultiPath++, a future prediction model that achieves state-of-the-art performance on popular benchmarks. MultiPath++ improves the MultiPath architecture by revisiting many design choices. The first key design difference is a departure from dense image-based encoding of the input world state in favor of a sparse encoding of heterogeneous scene elements: MultiPath++ consumes compact and efficient polylines to describe road features, and raw agent state information directly (e.g., position, velocity, acceleration). We propose a context-aware fusion of these elements and develop a reusable multi-context gating fusion component. Second, we reconsider the choice of pre-defined, static anchors, and develop a way to learn latent anchor embeddings end-to-end in the model. Lastly, we explore ensembling and output aggregation techniques -- common in other ML domains -- and find effective variants for our probabilistic multimodal output representation. We perform an extensive ablation on these design choices, and show that our proposed model achieves state-of-the-art performance on the Argoverse Motion Forecasting Competition and the Waymo Open Dataset Motion Prediction Challenge.
Evaluation of Machine Learning Techniques for Forecast Uncertainty Quantification
Sacco, Maximiliano A., Ruiz, Juan J., Pulido, Manuel, Tandeo, Pierre
Producing an accurate weather forecast and a reliable quantification of its uncertainty is an open scientific challenge. Ensemble forecasting is, so far, the most successful approach to produce relevant forecasts along with an estimation of their uncertainty. The main limitations of ensemble forecasting are the high computational cost and the difficulty to capture and quantify different sources of uncertainty, particularly those associated with model errors. In this work proof-of-concept model experiments are conducted to examine the performance of ANNs trained to predict a corrected state of the system and the state uncertainty using only a single deterministic forecast as input. We compare different training strategies: one based on a direct training using the mean and spread of an ensemble forecast as target, the other ones rely on an indirect training strategy using a deterministic forecast as target in which the uncertainty is implicitly learned from the data. For the last approach two alternative loss functions are proposed and evaluated, one based on the data observation likelihood and the other one based on a local estimation of the error. The performance of the networks is examined at different lead times and in scenarios with and without model errors. Experiments using the Lorenz'96 model show that the ANNs are able to emulate some of the properties of ensemble forecasts like the filtering of the most unpredictable modes and a state-dependent quantification of the forecast uncertainty. Moreover, ANNs provide a reliable estimation of the forecast uncertainty in the presence of model error.
K-means clustering
The topic I will try to explain today is K-means clustering. First, you might be wondering what the "K" means. K is a parameter that corresponds to the number of clusters you are trying to detect. For example, in order to detect 3 clusters like on the image on top, you would need to use K 3. But what does it mean?
Parallel XGBoost with Dask in Python
Out of the box, XGBoost cannot be trained on datasets larger than your computer memory; Python will throw a MemoryError. This tutorial will show you how to go beyond your local machine limitations by leveraging distributed XGBoost with Dask with only minor changes to your existing code. Here is the code we will use if you want to jump right in. By default, XGBoost trains models sequentially. This is fine for basic projects, but as the size of your dataset and/or ML model grows, you may want to consider running XGBoost in distributed mode with Dask to speed up computations and reduce the burden on your local machine.
Fish Weight Prediction (Regression Analysis for beginners) -- Part 1
Today we will predict(estimate) the weight of the fish based on species name of fish, vertical length, diagonal length, cross length, height, and diagonal width using linear models. I will introduce the top town approach to solving the problem, which I explained in the previous article. First In part 1.1 I will build a model and then in part 1.2 I will try to explain how each algorithm and methods work. This is a regression analysis problem for beginners. Understanding the main principles and methods of building this kind of problem will help to build your own ML regression model such as (house price prediction, etc.)
Top 10 Latest Machine Learning Algorithms to Know for 2022
In a world where all the manual tasks are automated, machine learning algorithms can help computers in playing chess, get smarter and to perform surgeries. One of the vital features of this revolution is how computing tools and techniques have been democratized. Machine learning can be supervised, unsupervised, semi-supervised and reinforcement learning. If you are one of the data scientists or machine learning enthusiasts then you should get a hang of the machine learning algorithms. Here are the top 10 latest machine learning algorithms to explore in 2022.
Understanding Tree Models
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