9,829 research outputs found
Autoencoders for strategic decision support
In the majority of executive domains, a notion of normality is involved in
most strategic decisions. However, few data-driven tools that support strategic
decision-making are available. We introduce and extend the use of autoencoders
to provide strategically relevant granular feedback. A first experiment
indicates that experts are inconsistent in their decision making, highlighting
the need for strategic decision support. Furthermore, using two large
industry-provided human resources datasets, the proposed solution is evaluated
in terms of ranking accuracy, synergy with human experts, and dimension-level
feedback. This three-point scheme is validated using (a) synthetic data, (b)
the perspective of data quality, (c) blind expert validation, and (d)
transparent expert evaluation. Our study confirms several principal weaknesses
of human decision-making and stresses the importance of synergy between a model
and humans. Moreover, unsupervised learning and in particular the autoencoder
are shown to be valuable tools for strategic decision-making
Typical Phone Use Habits: Intense Use Does Not Predict Negative Well-Being
Not all smartphone owners use their device in the same way. In this work, we
uncover broad, latent patterns of mobile phone use behavior. We conducted a
study where, via a dedicated logging app, we collected daily mobile phone
activity data from a sample of 340 participants for a period of four weeks.
Through an unsupervised learning approach and a methodologically rigorous
analysis, we reveal five generic phone use profiles which describe at least 10%
of the participants each: limited use, business use, power use, and
personality- & externally induced problematic use. We provide evidence that
intense mobile phone use alone does not predict negative well-being. Instead,
our approach automatically revealed two groups with tendencies for lower
well-being, which are characterized by nightly phone use sessions.Comment: 10 pages, 6 figures, conference pape
Deep Divergence-Based Approach to Clustering
A promising direction in deep learning research consists in learning
representations and simultaneously discovering cluster structure in unlabeled
data by optimizing a discriminative loss function. As opposed to supervised
deep learning, this line of research is in its infancy, and how to design and
optimize suitable loss functions to train deep neural networks for clustering
is still an open question. Our contribution to this emerging field is a new
deep clustering network that leverages the discriminative power of
information-theoretic divergence measures, which have been shown to be
effective in traditional clustering. We propose a novel loss function that
incorporates geometric regularization constraints, thus avoiding degenerate
structures of the resulting clustering partition. Experiments on synthetic
benchmarks and real datasets show that the proposed network achieves
competitive performance with respect to other state-of-the-art methods, scales
well to large datasets, and does not require pre-training steps
Neural Vector Spaces for Unsupervised Information Retrieval
We propose the Neural Vector Space Model (NVSM), a method that learns
representations of documents in an unsupervised manner for news article
retrieval. In the NVSM paradigm, we learn low-dimensional representations of
words and documents from scratch using gradient descent and rank documents
according to their similarity with query representations that are composed from
word representations. We show that NVSM performs better at document ranking
than existing latent semantic vector space methods. The addition of NVSM to a
mixture of lexical language models and a state-of-the-art baseline vector space
model yields a statistically significant increase in retrieval effectiveness.
Consequently, NVSM adds a complementary relevance signal. Next to semantic
matching, we find that NVSM performs well in cases where lexical matching is
needed.
NVSM learns a notion of term specificity directly from the document
collection without feature engineering. We also show that NVSM learns
regularities related to Luhn significance. Finally, we give advice on how to
deploy NVSM in situations where model selection (e.g., cross-validation) is
infeasible. We find that an unsupervised ensemble of multiple models trained
with different hyperparameter values performs better than a single
cross-validated model. Therefore, NVSM can safely be used for ranking documents
without supervised relevance judgments.Comment: TOIS 201
Outlier ensembles: A robust method for damage detection and unsupervised feature extraction from high-dimensional data
Outlier ensembles are shown to provide a robust method for damage detection and dimension reduction via a wholly unsupervised framework. Most interestingly, when utilised for feature extraction, the proposed heuristic defines features that enable near-equivalent classification performance (95.85%) when compared to the features found (in previous work) through supervised techniques (97.39%) — specifically, a genetic algorithm. This is significant for practical applications of structural health monitoring, where labelled data are rarely available during data mining. Ensemble analysis is applied to practical examples of problematic engineering data; two case studies are presented in this work. Case study I illustrates how outlier ensembles can be used to expose outliers hidden within a dataset. Case study II demonstrates how ensembles can be utilised as a tool for robust outlier analysis and feature extraction in a noisy, high-dimensional feature-space
clusterBMA: Bayesian model averaging for clustering
Various methods have been developed to combine inference across multiple sets
of results for unsupervised clustering, within the ensemble clustering
literature. The approach of reporting results from one `best' model out of
several candidate clustering models generally ignores the uncertainty that
arises from model selection, and results in inferences that are sensitive to
the particular model and parameters chosen. Bayesian model averaging (BMA) is a
popular approach for combining results across multiple models that offers some
attractive benefits in this setting, including probabilistic interpretation of
the combined cluster structure and quantification of model-based uncertainty.
In this work we introduce clusterBMA, a method that enables weighted model
averaging across results from multiple unsupervised clustering algorithms. We
use clustering internal validation criteria to develop an approximation of the
posterior model probability, used for weighting the results from each model.
From a consensus matrix representing a weighted average of the clustering
solutions across models, we apply symmetric simplex matrix factorisation to
calculate final probabilistic cluster allocations. In addition to outperforming
other ensemble clustering methods on simulated data, clusterBMA offers unique
features including probabilistic allocation to averaged clusters, combining
allocation probabilities from 'hard' and 'soft' clustering algorithms, and
measuring model-based uncertainty in averaged cluster allocation. This method
is implemented in an accompanying R package of the same name
Domain Agnostic Real-Valued Specificity Prediction
Sentence specificity quantifies the level of detail in a sentence,
characterizing the organization of information in discourse. While this
information is useful for many downstream applications, specificity prediction
systems predict very coarse labels (binary or ternary) and are trained on and
tailored toward specific domains (e.g., news). The goal of this work is to
generalize specificity prediction to domains where no labeled data is available
and output more nuanced real-valued specificity ratings.
We present an unsupervised domain adaptation system for sentence specificity
prediction, specifically designed to output real-valued estimates from binary
training labels. To calibrate the values of these predictions appropriately, we
regularize the posterior distribution of the labels towards a reference
distribution. We show that our framework generalizes well to three different
domains with 50%~68% mean absolute error reduction than the current
state-of-the-art system trained for news sentence specificity. We also
demonstrate the potential of our work in improving the quality and
informativeness of dialogue generation systems.Comment: AAAI 2019 camera read
- …