323,144 research outputs found
Active Learning with Expert Advice
Conventional learning with expert advice methods assumes a learner is always
receiving the outcome (e.g., class labels) of every incoming training instance
at the end of each trial. In real applications, acquiring the outcome from
oracle can be costly or time consuming. In this paper, we address a new problem
of active learning with expert advice, where the outcome of an instance is
disclosed only when it is requested by the online learner. Our goal is to learn
an accurate prediction model by asking the oracle the number of questions as
small as possible. To address this challenge, we propose a framework of active
forecasters for online active learning with expert advice, which attempts to
extend two regular forecasters, i.e., Exponentially Weighted Average Forecaster
and Greedy Forecaster, to tackle the task of active learning with expert
advice. We prove that the proposed algorithms satisfy the Hannan consistency
under some proper assumptions, and validate the efficacy of our technique by an
extensive set of experiments.Comment: Appears in Proceedings of the Twenty-Ninth Conference on Uncertainty
in Artificial Intelligence (UAI2013
Online active learning with expert advice
Singapore National Research Foundation under International Research Centre @ Singapore Funding Initiativ
Dynamic Ensemble Active Learning: A Non-Stationary Bandit with Expert Advice
Active learning aims to reduce annotation cost by predicting which samples
are useful for a human teacher to label. However it has become clear there is
no best active learning algorithm. Inspired by various philosophies about what
constitutes a good criteria, different algorithms perform well on different
datasets. This has motivated research into ensembles of active learners that
learn what constitutes a good criteria in a given scenario, typically via
multi-armed bandit algorithms. Though algorithm ensembles can lead to better
results, they overlook the fact that not only does algorithm efficacy vary
across datasets, but also during a single active learning session. That is, the
best criteria is non-stationary. This breaks existing algorithms' guarantees
and hampers their performance in practice. In this paper, we propose dynamic
ensemble active learning as a more general and promising research direction. We
develop a dynamic ensemble active learner based on a non-stationary multi-armed
bandit with expert advice algorithm. Our dynamic ensemble selects the right
criteria at each step of active learning. It has theoretical guarantees, and
shows encouraging results on popular datasets.Comment: This work has been accepted at ICPR2018 and won Piero Zamperoni Best
Student Paper Awar
Adaptive Selective Sampling for Online Prediction with Experts
We consider online prediction of a binary sequence with expert advice. For
this setting, we devise label-efficient forecasting algorithms, which use a
selective sampling scheme that enables collecting much fewer labels than
standard procedures, while still retaining optimal worst-case regret
guarantees. These algorithms are based on exponentially weighted forecasters,
suitable for settings with and without a perfect expert. For a scenario where
one expert is strictly better than the others in expectation, we show that the
label complexity of the label-efficient forecaster scales roughly as the square
root of the number of rounds. Finally, we present numerical experiments
empirically showing that the normalized regret of the label-efficient
forecaster can asymptotically match known minimax rates for pool-based active
learning, suggesting it can optimally adapt to benign settings
Lipschitz Adaptivity with Multiple Learning Rates in Online Learning
We aim to design adaptive online learning algorithms that take advantage of
any special structure that might be present in the learning task at hand, with
as little manual tuning by the user as possible. A fundamental obstacle that
comes up in the design of such adaptive algorithms is to calibrate a so-called
step-size or learning rate hyperparameter depending on variance, gradient
norms, etc. A recent technique promises to overcome this difficulty by
maintaining multiple learning rates in parallel. This technique has been
applied in the MetaGrad algorithm for online convex optimization and the Squint
algorithm for prediction with expert advice. However, in both cases the user
still has to provide in advance a Lipschitz hyperparameter that bounds the norm
of the gradients. Although this hyperparameter is typically not available in
advance, tuning it correctly is crucial: if it is set too small, the methods
may fail completely; but if it is taken too large, performance deteriorates
significantly. In the present work we remove this Lipschitz hyperparameter by
designing new versions of MetaGrad and Squint that adapt to its optimal value
automatically. We achieve this by dynamically updating the set of active
learning rates. For MetaGrad, we further improve the computational efficiency
of handling constraints on the domain of prediction, and we remove the need to
specify the number of rounds in advance.Comment: 22 pages. To appear in COLT 201
Evaluating the Effectiveness of Teaching Assistants in Active Learning Classrooms
Active learning classrooms (ALCs) support teaching approaches that foster greater interaction and student engagement. However, a common challenge for instructors who teach in ALCs is to provide adequate assistance to students while implementing collaborative activities. This study examined the impact of teaching assistants in a large ALC. The results showed that incorporating teaching assistants increases studentsâ access to expert advice during small group activities; further, students view the teaching assistants as supportive of their success in the classroom. Therefore, availability of teaching assistants for instructors teaching in large ALCs must be considered along with classroom design and pedagogical approach
Designing a physical activity parenting course : parental views on recruitment, content and delivery
Background
Many children do not engage in sufficient levels of physical activity (PA) and spend too much time screen-viewing (SV). High levels of SV (e.g. watching TV, playing video games and surfing the internet) and low levels of PA have been associated with adverse health outcomes. Parenting courses may hold promise as an intervention medium to change childrenâs PA and SV. The current study was formative work conducted to design a new parenting programme to increase childrenâs PA and reduce their SV. Specifically, we focussed on interest in a course, desired content and delivery style, barriers and facilitators to participation and opinions on control group provision.
Methods
In-depth telephone interviews were conducted with thirty two parents (29 female) of 6â8âyear olds. Data were analysed thematically. An anonymous online survey was also completed by 750 parents of 6â8âyear old children and descriptive statistics calculated.
Results
Interview participants were interested in a parenting course because they wanted general parenting advice and ideas to help their children be physically active. Parents indicated that they would benefit from knowing how to quantify their childâs PA and SV levels. Parents wanted practical ideas of alternatives to SV. Most parents would be unable to attend unless childcare was provided. Schools were perceived to be a trusted source of information about parenting courses and the optimal recruitment location. In terms of delivery style, the majority of parents stated they would prefer a group-based approach that provided opportunities for peer learning and support with professional input. Survey participants reported the timing of classes and the provision of childcare were essential factors that would affect participation. In terms of designing an intervention, the most preferred control group option was the opportunity to attend the same course at a later date.
Conclusions
Parents are interested in PA/SV parenting courses but the provision of child care is essential for attendance. Recruitment is likely to be facilitated via trusted sources. Parents want practical advice on how to overcome barriers and suggest advice is provided in a mutually supportive group experience with expert input
Farmer groups for animal health and welfare planning in European organic dairy herds
A set of common principles for active animal health and welfare planning in organic dairy farming has been developed in the ANIPLAN project group of seven European countries. Health and welfare planning is a farmerâowned process of continuous development and improvement and may be practised in many different ways. It should incorporate health promotion and disease handling, based on a strategy where assessment of current status and risks forms the basis for evaluation, action and review. Besides this, it should be 1) farm-specific, 2) involve external person(s) and 3) external knowledge, 4) be based on organic principles, 5) be written, and 6) acknowledge good aspects in addition to targeting the problem areas in order to stimulate the learning process. Establishing farmer groups seems to be a beneficial way of stimulating a dynamic development on the farms towards continuous improvement, as in this case with focus on animal health and welfare planning. Various factors influence the process in different contexts, e.g. geographical, cultural, traditional factors, and a proper analysis of the situation as well as the purpose of the group is necessary, and can relevantly be negotiated and coâdeveloped with farmers as well as facilitators before being implemented. Farmer groups based on farmerâtoâfarmer advice and coâdevelopment need a facilitator who takes on the role of facilitating the process and âdecodesâ himâ or herself from being âexpertâ
Universal Learning of Repeated Matrix Games
We study and compare the learning dynamics of two universal learning
algorithms, one based on Bayesian learning and the other on prediction with
expert advice. Both approaches have strong asymptotic performance guarantees.
When confronted with the task of finding good long-term strategies in repeated
2x2 matrix games, they behave quite differently.Comment: 16 LaTeX pages, 8 eps figure
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