12 research outputs found
Model Agnostic Explainable Selective Regression via Uncertainty Estimation
With the wide adoption of machine learning techniques, requirements have
evolved beyond sheer high performance, often requiring models to be
trustworthy. A common approach to increase the trustworthiness of such systems
is to allow them to refrain from predicting. Such a framework is known as
selective prediction. While selective prediction for classification tasks has
been widely analyzed, the problem of selective regression is understudied. This
paper presents a novel approach to selective regression that utilizes
model-agnostic non-parametric uncertainty estimation. Our proposed framework
showcases superior performance compared to state-of-the-art selective
regressors, as demonstrated through comprehensive benchmarking on 69 datasets.
Finally, we use explainable AI techniques to gain an understanding of the
drivers behind selective regression. We implement our selective regression
method in the open-source Python package doubt and release the code used to
reproduce our experiments
CASP-DM: Context Aware Standard Process for Data Mining
We propose an extension of the Cross Industry Standard Process for Data
Mining (CRISPDM) which addresses specific challenges of machine learning and
data mining for context and model reuse handling. This new general
context-aware process model is mapped with CRISP-DM reference model proposing
some new or enhanced outputs
Reframing in context: A systematic approach for model reuse in machine learning
We describe a systematic approach called reframing, defined as the process of preparing a machine learning model (e.g., a classifier) to perform well over a range of operating contexts. One way to achieve this is by constructing a versatile model, which is not fitted to a particular context, and thus enables model reuse. We formally characterise reframing in terms of a taxonomy of context changes that may be encountered and distinguish it from model retraining and revision. We then identify three main kinds of reframing: input reframing, output reframing and structural reframing. We proceed by reviewing areas and problems where some notion of reframing has already been developed and shown useful, if under different names: re-optimising, adapting, tuning, thresholding, etc. This exploration of the landscape of reframing allows us to identify opportunities where reframing might be possible and useful. Finally, we describe related approaches in terms of the problems they address or the kind of solutions they obtain. The paper closes with a re-interpretation of the model development and deployment process with the use of reframing.We thank the anonymous reviewers for their comments, which have helped to improve this paper significantly. This work was supported by the REFRAME project, granted by the European Coordinated Research on Long-term Challenges in Information and Communication Sciences Technologies ERA-Net (CHIST-ERA), funded by their respective national funding agencies in the UK (EPSRC, EP/K018728), France and Spain (MINECO, PCIN-2013-037). It has also been partially supported by the EU (FEDER) and Spanish MINECO grant TIN2015-69175-C4-1-R and by Generalitat Valenciana PROMETEOII/2015/013.Hernández Orallo, J.; MartÃnez Usó, A.; Prudencio, RBC.; Kull, M.; Flach, P.; Ahmed, CF.; Lachiche, N. (2016). Reframing in context: A systematic approach for model reuse in machine learning. AI Communications. 29(5):551-566. https://doi.org/10.3233/AIC-160705S55156629
Machine Learning with a Reject Option: A survey
Machine learning models always make a prediction, even when it is likely to
be inaccurate. This behavior should be avoided in many decision support
applications, where mistakes can have severe consequences. Albeit already
studied in 1970, machine learning with rejection recently gained interest. This
machine learning subfield enables machine learning models to abstain from
making a prediction when likely to make a mistake.
This survey aims to provide an overview on machine learning with rejection.
We introduce the conditions leading to two types of rejection, ambiguity and
novelty rejection, which we carefully formalize. Moreover, we review and
categorize strategies to evaluate a model's predictive and rejective quality.
Additionally, we define the existing architectures for models with rejection
and describe the standard techniques for learning such models. Finally, we
provide examples of relevant application domains and show how machine learning
with rejection relates to other machine learning research areas
Cost-Sensitive Classification Methods for the Detection of Smuggled Nuclear Material in Cargo Containers
Classification problems arise in so many different parts of life – from sorting machine parts to diagnosing a disease. Humans make these classifications utilizing vast amounts of data, filtering observations for useful information, and then making a decision based on a subjective level of cost/risk of classifying objects incorrectly.
This study investigates the translation of the human decision process into a mathematical problem in the context of a border security problem: How does one find special nuclear material being smuggled inside large cargo crates while balancing the cost of invasively searching suspect containers against the risk of al lowing radioactive material to escape detection? This may be phrased as a classification problem in which one classifies cargo containers into two categories – those containing a smuggled source and those containing only innocuous cargo. This task presents numerous challenges, e.g., the stochastic nature of radiation and the low signal-to-noise ratio caused by background radiation and cargo shielding.
In the course of this work, we will break the analysis of this problem into three major sections – the development of an optimal decision rule, the choice of most useful measurements or features, and the sensitivity of developed algorithms to physical variations. This will include an examination of how accounting for the cost/risk of a decision affects the formulation of our classification problem.
Ultimately, a support vector machine (SVM) framework with F -score feature selection will be developed to provide nearly optimal classification given a constraint on the reliability of detection provided by our algorithm. In particular, this can decrease the fraction of false positives by an order of magnitude over current methods. The proposed method also takes into account the relationship between measurements, whereas current methods deal with detectors independently of one another
Deep Neural Network Benchmarks for Selective Classification
With the increasing deployment of machine learning models in many
socially-sensitive tasks, there is a growing demand for reliable and
trustworthy predictions. One way to accomplish these requirements is to allow a
model to abstain from making a prediction when there is a high risk of making
an error. This requires adding a selection mechanism to the model, which
selects those examples for which the model will provide a prediction. The
selective classification framework aims to design a mechanism that balances the
fraction of rejected predictions (i.e., the proportion of examples for which
the model does not make a prediction) versus the improvement in predictive
performance on the selected predictions. Multiple selective classification
frameworks exist, most of which rely on deep neural network architectures.
However, the empirical evaluation of the existing approaches is still limited
to partial comparisons among methods and settings, providing practitioners with
little insight into their relative merits. We fill this gap by benchmarking 18
baselines on a diverse set of 44 datasets that includes both image and tabular
data. Moreover, there is a mix of binary and multiclass tasks. We evaluate
these approaches using several criteria, including selective error rate,
empirical coverage, distribution of rejected instance's classes, and
performance on out-of-distribution instances. The results indicate that there
is not a single clear winner among the surveyed baselines, and the best method
depends on the users' objectives
Optimisation des Systèmes Multimodaux pour l’Identification dans l’Imagerie
Parmi les médias les plus populaires qui ont pris une place incontournable pour le développement des systèmes de reconnaissances biométriques en général et les systèmes de la reconnaissance de visage en particulier on trouve l’Image.
L’une des utilisations les plus courantes des images est l’identification/vérification en biométrie qui connaît un intérêt grandissant depuis quelques années. L’efficacité des techniques d’identification en imagerie est aujourd’hui très fortement liée à des contraintes fortes imposées à l’utilisateur. Une voie de recherche actuelle se tourne donc vers la gestion de situations où l’acquisition des données est moins contrainte. Finalement, l’usage d’une seule modalité est souvent limité en termes de performance ou de difficultés d’usage, c’est pourquoi il apparaît intéressant d’évaluer l’apport de la multi-modalité dans ce contexte.
L’objectif de la thèse est de mener un travail pour poursuivre une recherche tournée à la fois vers les techniques d’optimisation basées d’une part sur les descripteurs hybrides et les patchs ainsi que leurs techniques de fusions, et d’autre part sur le Deep Learning (Transfer Learning). Nous nous intéressons plus particulièrement à l’image du visage et nos approches sont validées sur plusieurs bases de données universelles pour défier tous les aléas d’acquisition et d’environnements non contrôlés
Multivariate classification of gene expression microarray data
L'expressiódels gens obtinguts de l'anà liside microarrays s'utilitza en molts casos, per classificar les cèllules. En aquestatesi, unaversióprobabilÃstica del mètodeDiscriminant Partial Least Squares (p-DPLS)s'utilitza per classificar les mostres de les expressions delsseus gens. p-DPLS esbasa en la regla de Bayes de la probabilitat a posteriori. Aquestsclassificadorssónforaçats a classficarsempre.Per superaraquestalimitaciós'haimplementatl'opció de rebuig.Aquestaopciópermetrebutjarlesmostresamb alt riscd'errors de classificació (és a dir, mostresambigüesi outliers).Aquestaopció de rebuigcombinacriterisbasats en els residuals x, el leverage ielsvalorspredits. A més,esdesenvolupa un mètode de selecció de variables per triarels gens mésrellevants, jaque la majoriadels gens analitzatsamb un microarraysónirrellevants per al propòsit particular de classificacióI podenconfondre el classificador. Finalment, el DPLSs'estenen a la classificació multi-classemitjançant la combinació de PLS ambl'anà lisidiscriminant lineal