56 research outputs found
A Multi-Armed Bandit to Smartly Select a Training Set from Big Medical Data
With the availability of big medical image data, the selection of an adequate
training set is becoming more important to address the heterogeneity of
different datasets. Simply including all the data does not only incur high
processing costs but can even harm the prediction. We formulate the smart and
efficient selection of a training dataset from big medical image data as a
multi-armed bandit problem, solved by Thompson sampling. Our method assumes
that image features are not available at the time of the selection of the
samples, and therefore relies only on meta information associated with the
images. Our strategy simultaneously exploits data sources with high chances of
yielding useful samples and explores new data regions. For our evaluation, we
focus on the application of estimating the age from a brain MRI. Our results on
7,250 subjects from 10 datasets show that our approach leads to higher accuracy
while only requiring a fraction of the training data.Comment: MICCAI 2017 Proceeding
Learning Active Learning from Data
In this paper, we suggest a novel data-driven approach to active learning
(AL). The key idea is to train a regressor that predicts the expected error
reduction for a candidate sample in a particular learning state. By formulating
the query selection procedure as a regression problem we are not restricted to
working with existing AL heuristics; instead, we learn strategies based on
experience from previous AL outcomes. We show that a strategy can be learnt
either from simple synthetic 2D datasets or from a subset of domain-specific
data. Our method yields strategies that work well on real data from a wide
range of domains
An Efficient Learning of Constraints For Semi-Supervised Clustering using Neighbour Clustering Algorithm
Data mining is the process of finding the previously unknown and potentially interesting patterns and relation in database. Data mining is the step in the knowledge discovery in database process (KDD) .The structures that are the outcome of the data mining process must meet certain condition so that these can be considered as knowledge. These conditions are validity, understandability, utility, novelty, interestingness. Researcher identifies two fundamental goals of data mining: prediction and description. The proposed research work suggests the semi-supervised clustering problem where to know (with varying degree of certainty) that some sample pairs are (or are not) in the same class. A probabilistic model for semi-supervised clustering based on Shared Semi-supervised Neighbor clustering (SSNC) that provides a principled framework for incorporating supervision into prototype-based clustering. Semi-supervised clustering that combines the constraint-based and fitness-based approaches in a unified model. The proposed method first divides the Constraint-sensitive assignment of instances to clusters, where points are assigned to clusters so that the overall distortion of the points from the cluster centroids is minimized, while a minimum number of must-link and cannot-link constraints are violated. Experimental results across UCL Machine learning semi-supervised dataset results show that the proposed method has higher F-Measures than many existing Semi-Supervised Clustering methods
Robustness of Bayesian Pool-based Active Learning Against Prior Misspecification
We study the robustness of active learning (AL) algorithms against prior
misspecification: whether an algorithm achieves similar performance using a
perturbed prior as compared to using the true prior. In both the average and
worst cases of the maximum coverage setting, we prove that all
-approximate algorithms are robust (i.e., near -approximate) if
the utility is Lipschitz continuous in the prior. We further show that
robustness may not be achieved if the utility is non-Lipschitz. This suggests
we should use a Lipschitz utility for AL if robustness is required. For the
minimum cost setting, we can also obtain a robustness result for approximate AL
algorithms. Our results imply that many commonly used AL algorithms are robust
against perturbed priors. We then propose the use of a mixture prior to
alleviate the problem of prior misspecification. We analyze the robustness of
the uniform mixture prior and show experimentally that it performs reasonably
well in practice.Comment: This paper is published at AAAI Conference on Artificial Intelligence
(AAAI 2016
- …