Goto

Collaborating Authors

 Performance Analysis


A Cross-lingual Natural Language Processing Framework for Infodemic Management

arXiv.org Artificial Intelligence

The COVID-19 pandemic has put immense pressure on health systems which are further strained due to the misinformation surrounding it. Under such a situation, providing the right information at the right time is crucial. There is a growing demand for the management of information spread using Artificial Intelligence. Hence, we have exploited the potential of Natural Language Processing for identifying relevant information that needs to be disseminated amongst the masses. In this work, we present a novel Cross-lingual Natural Language Processing framework to provide relevant information by matching daily news with trusted guidelines from the World Health Organization. The proposed pipeline deploys various techniques of NLP such as summarizers, word embeddings, and similarity metrics to provide users with news articles along with a corresponding healthcare guideline. A total of 36 models were evaluated and a combination of LexRank based summarizer on Word2Vec embedding with Word Mover distance metric outperformed all other models. This novel open-source approach can be used as a template for proactive dissemination of relevant healthcare information in the midst of misinformation spread associated with epidemics.


Cross Validation Machine Learning: K-Fold

#artificialintelligence

Cross-validation is used to evaluate machine learning models on a limited data sample.It estimates the skill of a machine learning model on unseen data. The techniques creates and validates given model multiple times. We have 2โ€“4 types of cross validation like Stratified, LOOCV, K-Fold etc. Here, we will study K-Fold technique. Let's split data 70:30, train model and test the given data-set to get accuracy.


Multi-Task Learning for Interpretable Weakly Labelled Sound Event Detection

arXiv.org Machine Learning

Weakly Labelled learning has garnered lot of attention in recent years due to its potential to scale Sound Event Detection (SED) and is formulated as Multiple Instance Learning (MIL) problem. This paper proposes a Multi-Task Learning (MTL) framework for learning from Weakly Labelled Audio data which encompasses the traditional MIL setup. To show the utility of proposed framework, we use the input TimeFrequency representation (T-F) reconstruction as the auxiliary task. We show that the chosen auxiliary task de-noises internal T-F representation and improves SED performance under noisy recordings. Our second contribution is introducing two step Attention Pooling mechanism. By having 2-steps in attention mechanism, the network retains better T-F level information without compromising SED performance. The visualisation of first step and second step attention weights helps in localising the audio-event in T-F domain. For evaluating the proposed framework, we remix the DCASE 2019 task 1 acoustic scene data with DCASE 2018 Task 2 sounds event data under 0, 10 and 20 db SNR resulting in a multi-class Weakly labelled SED problem. The proposed total framework outperforms existing benchmark models over all SNRs, specifically 22.3 %, 12.8 %, 5.9 % improvement over benchmark model on 0, 10 and 20 dB SNR respectively. We carry out ablation study to determine the contribution of each auxiliary task and 2-step Attention Pooling to the SED performance improvement. The code is publicly released


Post-selection inference with HSIC-Lasso

arXiv.org Machine Learning

Detecting influential features in complex (non-linear and/or high-dimensional) datasets is key for extracting the relevant information. Most of the popular selection procedures, however, require assumptions on the underlying data - such as distributional ones -, which barely agree with empirical observations. Therefore, feature selection based on nonlinear methods, such as the model-free HSIC-Lasso, is a more relevant approach. In order to ensure valid inference among the chosen features, the selection procedure must be accounted for. In this paper, we propose selective inference with HSIC-Lasso using the framework of truncated Gaussians together with the polyhedral lemma. Based on these theoretical foundations, we develop an algorithm allowing for low computational costs and the treatment of the hyper-parameter selection issue. The relevance of our method is illustrated using artificial and real-world datasets. In particular, our empirical findings emphasise that type-I error control at the considered level can be achieved.


Robustness against Relational Adversary

arXiv.org Machine Learning

Test-time adversarial attacks have posed serious challenges to the robustness of machine-learning models, and in many settings the adversarial perturbation need not be bounded by small $\ell_p$-norms. Motivated by the semantics-preserving attacks in vision and security domain, we investigate $\textit{relational adversaries}$, a broad class of attackers who create adversarial examples that are in a reflexive-transitive closure of a logical relation. We analyze the conditions for robustness and propose $\textit{normalize-and-predict}$ -- a learning framework with provable robustness guarantee. We compare our approach with adversarial training and derive an unified framework that provides benefits of both approaches. Guided by our theoretical findings, we apply our framework to image classification and malware detection. Results of both tasks show that attacks using relational adversaries frequently fool existing models, but our unified framework can significantly enhance their robustness.


Naive-Bayes Inference for Testing

#artificialintelligence

Probability is the cornerstone of Artificial Intelligence. The management of uncertainty is key to many applications of AI, such as machine learning, filtering, robotics, computer vision, NLP, search and so on. And no other sector is the management of uncertainty as crucial as it is in the health sector. At first glance, the false-negative seems more devastating. Of course, a false allergy test-result has the likely outcome of a GP administering a drug to you that could cause life-threatening issues.


Evaluating Model Robustness to Dataset Shift

arXiv.org Machine Learning

The environments in which we deploy machine learning (ML) algorithms rarely look exactly like the environments in which we collected our training data. Unfortunately, we lack methodology for evaluating how well an algorithm will generalize to new environments that differ in a structured way from the training data (i.e., the case of dataset shift (Quiรฑonero-Candela et al., 2009)). Such methodology is increasingly important as ML systems are being deployed across a number of industries, such as health care and personal finance, in which system performance translates directly to real-world outcomes. Further, as regulation and product reviews become more common across industries, system developers will be expected to produce evidence of the validity and safety of their systems. For example, the United States Food and Drug Administration (FDA) currently regulates ML systems for medical applications, requiring evidence for the validity of such systems before approval is granted (US Food and Drug Administration, 2019). Evaluation methods for assessing model validity have typically focused on how the model performs on data from the training distribution, known as internal validity. Powerful tools, such as cross-validation and the bootstrap, satisfy the assumption that the training and test data are drawn from the same distribution. However, these validation methods do not capture a model's ability to generalize to new environments, known as external validity (Campbell and Stanley, 1963). Currently, the main way to assess a model's external validity is to empirically evaluate performance on multiple, independently collected datasets (e.g.,


Sea-Net: Squeeze-And-Excitation Attention Net For Diabetic Retinopathy Grading

arXiv.org Artificial Intelligence

Diabetes is one of the most common disease in individuals. \textit{Diabetic retinopathy} (DR) is a complication of diabetes, which could lead to blindness. Automatic DR grading based on retinal images provides a great diagnostic and prognostic value for treatment planning. However, the subtle differences among severity levels make it difficult to capture important features using conventional methods. To alleviate the problems, a new deep learning architecture for robust DR grading is proposed, referred to as SEA-Net, in which, spatial attention and channel attention are alternatively carried out and boosted with each other, improving the classification performance. In addition, a hybrid loss function is proposed to further maximize the inter-class distance and reduce the intra-class variability. Experimental results have shown the effectiveness of the proposed architecture.


Predicting Classification Accuracy when Adding New Unobserved Classes

arXiv.org Artificial Intelligence

Multiclass classifiers are often designed and evaluated only on a sample from the classes on which they will eventually be applied. Hence, their final accuracy remains unknown. In this work we study how a classifier's performance over the initial class sample can be used to extrapolate its expected accuracy on a larger, unobserved set of classes. For this, we define a measure of separation between correct and incorrect classes that is independent of the number of classes: the reversed ROC (rROC), which is obtained by replacing the roles of classes and data-points in the common ROC. We show that the classification accuracy is a function of the rROC in multiclass classifiers, for which the learned representation of data from the initial class sample remains unchanged when new classes are added. Using these results we formulate a robust neural-network-based algorithm, CleaneX, which learns to estimate the accuracy of such classifiers on arbitrarily large sets of classes. Our method achieves remarkably better predictions than current state-of-the-art methods on both simulations and real datasets of object detection, face recognition, and brain decoding.


How to balance transformation decisions, feature selection, and model tuning vs time in text analytics?

#artificialintelligence

Being to new text analytics, I haven't gotten the hang of my typical ML workflow given how long processes take to run in the commonly large feature space of text analytics. I would like to know what the typical strategy is to balance effort/time in terms of optimizing transformation decision, feature down-selection, and model tuning. In an effort to get a sense of which of the decision points above I should run further tuning on, I ran untuned RF, Logistic, Naive Bayes, SGD, and KNN models on (with cross validation). No clear decision point was commonly "better" in the resulting f-1 scores, and the difference is often noteworthy. As I have no bias towards a particular algorithm type (only the best f-1 score), I'm stuck in a quandry-- I have not successfully narrowed my decision space enough.