28 research outputs found
Many Ways to Be Lonely: Fine-Grained Characterization of Loneliness and Its Potential Changes in COVID-19
Loneliness has been associated with negative outcomes for physical and mental
health. Understanding how people express and cope with various forms of
loneliness is critical for early screening and targeted interventions to reduce
loneliness, particularly among vulnerable groups such as young adults. To
examine how different forms of loneliness and coping strategies manifest in
loneliness self-disclosure, we built a dataset, FIG-Loneliness (FIne-Grained
Loneliness) by using Reddit posts in two young adult-focused forums and two
loneliness related forums consisting of a diverse age group. We provided
annotations by trained human annotators for binary and fine-grained loneliness
classifications of the posts. Trained on FIG-Loneliness, two BERT-based models
were used to understand loneliness forms and authors' coping strategies in
these forums. Our binary loneliness classification achieved an accuracy above
97%, and fine-grained loneliness category classification reached an average
accuracy of 77% across all labeled categories. With FIG-Loneliness and model
predictions, we found that loneliness expressions in the young adults related
forums were distinct from other forums. Those in young adult-focused forums
were more likely to express concerns pertaining to peer relationship, and were
potentially more sensitive to geographical isolation impacted by the COVID-19
pandemic lockdown. Also, we showed that different forms of loneliness have
differential use in coping strategies
A Unifying Framework for Combining Complementary Strengths of Humans and ML toward Better Predictive Decision-Making
Hybrid human-ML systems are increasingly in charge of consequential decisions
in a wide range of domains. A growing body of empirical and theoretical work
has advanced our understanding of these systems. However, existing empirical
results are mixed, and theoretical proposals are often mutually incompatible.
In this work, we propose a unifying framework for understanding conditions
under which combining the complementary strengths of humans and ML leads to
higher quality decisions than those produced by each of them individually -- a
state which we refer to as human-ML complementarity. We focus specifically on
the context of human-ML predictive decision-making and investigate optimal ways
of combining human and ML predictive decisions, accounting for the underlying
sources of variation in their judgments. Within this scope, we present two
crucial contributions. First, taking a computational perspective of
decision-making and drawing upon prior literature in psychology, machine
learning, and human-computer interaction, we introduce a taxonomy
characterizing a wide range of criteria across which human and machine
decision-making differ. Second, formalizing our taxonomy allows us to study how
human and ML predictive decisions should be aggregated optimally. We show that
our proposed framework encompasses several existing models of human-ML
complementarity as special cases. Last but not least, an initial exploratory
analysis of our framework presents a critical insight for future work in
human-ML complementarity: the mechanism by which we combine human and ML
judgments should be informed by the underlying causes of divergence in their
decisions.Comment: 21 pages, 1 figur
Modeling Attrition in Recommender Systems with Departing Bandits
Traditionally, when recommender systems are formalized as multi-armed
bandits, the policy of the recommender system influences the rewards accrued,
but not the length of interaction. However, in real-world systems, dissatisfied
users may depart (and never come back). In this work, we propose a novel
multi-armed bandit setup that captures such policy-dependent horizons. Our
setup consists of a finite set of user types, and multiple arms with Bernoulli
payoffs. Each (user type, arm) tuple corresponds to an (unknown) reward
probability. Each user's type is initially unknown and can only be inferred
through their response to recommendations. Moreover, if a user is dissatisfied
with their recommendation, they might depart the system. We first address the
case where all users share the same type, demonstrating that a recent UCB-based
algorithm is optimal. We then move forward to the more challenging case, where
users are divided among two types. While naive approaches cannot handle this
setting, we provide an efficient learning algorithm that achieves
regret, where is the number of users.Comment: Accepted at AAAI 202
A Field Test of Bandit Algorithms for Recommendations: Understanding the Validity of Assumptions on Human Preferences in Multi-armed Bandits
Personalized recommender systems suffuse modern life, shaping what media we
read and what products we consume. Algorithms powering such systems tend to
consist of supervised learning-based heuristics, such as latent factor models
with a variety of heuristically chosen prediction targets. Meanwhile,
theoretical treatments of recommendation frequently address the
decision-theoretic nature of the problem, including the need to balance
exploration and exploitation, via the multi-armed bandits (MABs) framework.
However, MAB-based approaches rely heavily on assumptions about human
preferences. These preference assumptions are seldom tested using human subject
studies, partly due to the lack of publicly available toolkits to conduct such
studies. In this work, we conduct a study with crowdworkers in a comics
recommendation MABs setting. Each arm represents a comic category, and users
provide feedback after each recommendation. We check the validity of core MABs
assumptions-that human preferences (reward distributions) are fixed over
time-and find that they do not hold. This finding suggests that any MAB
algorithm used for recommender systems should account for human preference
dynamics. While answering these questions, we provide a flexible experimental
framework for understanding human preference dynamics and testing MABs
algorithms with human users. The code for our experimental framework and the
collected data can be found at
https://github.com/HumainLab/human-bandit-evaluation.Comment: Accepted to CHI. 16 pages, 6 figure
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A novel flow-guide device for uniform exhaust in a central air exhaust ventilation system
Exhaust ventilation system with one central fan and multiple terminals has been widely used for the heat and contaminant removal in building environment. Conventional design without pressure balancing leads to uneven distribution of exhaust airflow rate among the multiple outlets. Existed balancing methods usually uses dampers (constant-air-volume valve or regulating valve), tapered duct, or varied inlet area. However, these methods result in higher fan energy consumption, or complicated construction and on-site commissioning. In this paper, a flow-guide device was developed for adjusting the pressure distribution of duct branches. This new device is integrated with the interflow Tee-junction and does not need any commissioning or regulating. The resistance performance of the device responding to the structural parameter was derived using the CFD simulation and experiment. The negative direct resistance featured by the device was found to effectively benefit exhaust at the outlets farther away from the central fan. The ductwork hydraulic model based on the Bernoulli's law of airflow and the fitted resistance correlations were further proposed to fulfill the parametric design. Finally, full-scale test was carried out for a central exhaust system installed with the flow-guide devices referring to a factory workshop with heat and contaminant sources. Compared to the system without the devices, the total rate of the system increased by 25%. Discrepancy of exhaust rate decreased by 78% and uneven degree decreased by 82%, which well meets the engineering balancing requirement. Meanwhile, total resistance of the system reduced 23.8% owing to the negative loss the devices bring