3,811 research outputs found
Simultaneous adaptation to the margin and to complexity in classification
We consider the problem of adaptation to the margin and to complexity in
binary classification. We suggest an exponential weighting aggregation scheme.
We use this aggregation procedure to construct classifiers which adapt
automatically to margin and complexity. Two main examples are worked out in
which adaptivity is achieved in frameworks proposed by Steinwart and Scovel
[Learning Theory. Lecture Notes in Comput. Sci. 3559 (2005) 279--294. Springer,
Berlin; Ann. Statist. 35 (2007) 575--607] and Tsybakov [Ann. Statist. 32 (2004)
135--166]. Adaptive schemes, like ERM or penalized ERM, usually involve a
minimization step. This is not the case for our procedure.Comment: Published in at http://dx.doi.org/10.1214/009053607000000055 the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Compact Personalized Models for Neural Machine Translation
We propose and compare methods for gradient-based domain adaptation of
self-attentive neural machine translation models. We demonstrate that a large
proportion of model parameters can be frozen during adaptation with minimal or
no reduction in translation quality by encouraging structured sparsity in the
set of offset tensors during learning via group lasso regularization. We
evaluate this technique for both batch and incremental adaptation across
multiple data sets and language pairs. Our system architecture - combining a
state-of-the-art self-attentive model with compact domain adaptation - provides
high quality personalized machine translation that is both space and time
efficient.Comment: Published at the 2018 Conference on Empirical Methods in Natural
Language Processin
Effectiveness of Corporate Social Media Activities to Increase Relational Outcomes
This study applies social media analytics to investigate the impact of different corporate social media activities on user word of mouth and attitudinal loyalty. We conduct a multilevel analysis of approximately 5 million tweets regarding the main Twitter accounts of 28 large global companies. We empirically identify different social media activities in terms of social media management strategies (using social media management tools or the web-frontend client), account types (broadcasting or receiving information), and communicative approaches (conversational or disseminative). We find positive effects of social media management tools, broadcasting accounts, and conversational communication on public perception
Extracting the Italian output gap: a Bayesian approach
During the last decades particular effort has been directed towards
understanding and predicting the relevant state of the business cycle with the
objective of decomposing permanent shocks from those having only a transitory
impact on real output. This trend--cycle decomposition has a relevant impact on
several economic and fiscal variables and constitutes by itself an important
indicator for policy purposes. This paper deals with trend--cycle decomposition
for the Italian economy having some interesting peculiarities which makes it
attractive to analyse from both a statistic and an historical perspective. We
propose an univariate model for the quarterly real GDP, subsequently extended
to include the price dynamics through a Phillips curve. This study considers a
series of the Italian quarterly real GDP recently released by OECD which
includes both the 1960s and the recent global financial crisis of 2007--2008.
Parameters estimate as well as the signal extraction are performed within the
Bayesian paradigm which effectively handles complex models where the parameters
enter the log--likelihood function in a strongly nonlinear way. A new Adaptive
Independent Metropolis--within--Gibbs sampler is then developed to efficiently
simulate the parameters of the unobserved cycle. Our results suggest that
inflation influences the Output Gap estimate, making the extracted Italian OG
an important indicator of inflation pressures on the real side of the economy,
as stated by the Phillips theory. Moreover, our estimate of the sequence of
peaks and troughs of the Output Gap is in line with the OECD official dating of
the Italian business cycle
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