31,254 research outputs found
How Algorithmic Confounding in Recommendation Systems Increases Homogeneity and Decreases Utility
Recommendation systems are ubiquitous and impact many domains; they have the
potential to influence product consumption, individuals' perceptions of the
world, and life-altering decisions. These systems are often evaluated or
trained with data from users already exposed to algorithmic recommendations;
this creates a pernicious feedback loop. Using simulations, we demonstrate how
using data confounded in this way homogenizes user behavior without increasing
utility
The SECURE collaboration model
The SECURE project has shown how trust can be made computationally tractable while retaining a reasonable connection with human and social notions of trust. SECURE has produced a well-founded theory of trust that has been tested and refined through use in real software such as collaborative spam filtering and electronic purse. The software comprises the SECURE kernel with extensions for policy specification by application developers. It has yet to be applied to large-scale, multi-domain distributed systems taking different application contexts into account. The project has not considered privacy in evidence distribution, a crucial issue for many application domains, including public services such as healthcare and police. The SECURE collaboration model has similarities with the trust domain concept, embodying the interaction set of a principal, but SECURE is primarily concerned with pseudonymous entities rather than domain-structured systems
Selection Bias in News Coverage: Learning it, Fighting it
News entities must select and filter the coverage they broadcast through
their respective channels since the set of world events is too large to be
treated exhaustively. The subjective nature of this filtering induces biases
due to, among other things, resource constraints, editorial guidelines,
ideological affinities, or even the fragmented nature of the information at a
journalist's disposal. The magnitude and direction of these biases are,
however, widely unknown. The absence of ground truth, the sheer size of the
event space, or the lack of an exhaustive set of absolute features to measure
make it difficult to observe the bias directly, to characterize the leaning's
nature and to factor it out to ensure a neutral coverage of the news. In this
work, we introduce a methodology to capture the latent structure of media's
decision process on a large scale. Our contribution is multi-fold. First, we
show media coverage to be predictable using personalization techniques, and
evaluate our approach on a large set of events collected from the GDELT
database. We then show that a personalized and parametrized approach not only
exhibits higher accuracy in coverage prediction, but also provides an
interpretable representation of the selection bias. Last, we propose a method
able to select a set of sources by leveraging the latent representation. These
selected sources provide a more diverse and egalitarian coverage, all while
retaining the most actively covered events
Adapting Triplet Importance of Implicit Feedback for Personalized Recommendation
Implicit feedback is frequently used for developing personalized
recommendation services due to its ubiquity and accessibility in real-world
systems. In order to effectively utilize such information, most research adopts
the pairwise ranking method on constructed training triplets (user, positive
item, negative item) and aims to distinguish between positive items and
negative items for each user. However, most of these methods treat all the
training triplets equally, which ignores the subtle difference between
different positive or negative items. On the other hand, even though some other
works make use of the auxiliary information (e.g., dwell time) of user
behaviors to capture this subtle difference, such auxiliary information is hard
to obtain. To mitigate the aforementioned problems, we propose a novel training
framework named Triplet Importance Learning (TIL), which adaptively learns the
importance score of training triplets. We devise two strategies for the
importance score generation and formulate the whole procedure as a bilevel
optimization, which does not require any rule-based design. We integrate the
proposed training procedure with several Matrix Factorization (MF)- and Graph
Neural Network (GNN)-based recommendation models, demonstrating the
compatibility of our framework. Via a comparison using three real-world
datasets with many state-of-the-art methods, we show that our proposed method
outperforms the best existing models by 3-21\% in terms of Recall@k for the
top-k recommendation
Biases in scholarly recommender systems: impact, prevalence, and mitigation
We create a simulated financial market and examine the effect of different levels of active and passive investment on fundamental market efficiency. In our simulated market, active, passive, and random investors interact with each other through issuing orders. Active and passive investors select their portfolio weights by optimizing Markowitz-based utility functions. We find that higher fractions of active investment within a market lead to an increased fundamental market efficiency. The marginal increase in fundamental market efficiency per additional active investor is lower in markets with higher levels of active investment. Furthermore, we find that a large fraction of passive investors within a market may facilitate technical price bubbles, resulting in market failure. By examining the effect of specific parameters on market outcomes, we find that that lower transaction costs, lower individual forecasting errors of active investors, and less restrictive portfolio constraints tend to increase fundamental market efficiency in the market
Ethical aspects of multi-stakeholder recommendation systems
This article analyses the ethical aspects of multistakeholder recommendation systems (RSs). Following the most common approach in the literature, we assume a consequentialist framework to introduce the main concepts of multistakeholder recommendation. We then consider three research questions: who are the stakeholders in a RS? How are their interests taken into account when formulating a recommendation? And, what is the scientific paradigm underlying RSs? Our main finding is that multistakeholder RSs (MRSs) are designed and theorised, methodologically, according to neoclassical welfare economics. We consider and reply to some methodological objections to MRSs on this basis, concluding that the multistakeholder approach offers the resources to understand the normative social dimension of RS
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