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Rethinking Recommender Systems: Beyond Predicting User-Item Interactions to Understanding the Decision-Making Process


Core Concepts
Recommender systems should be viewed as dynamic processes that aim to understand and predict user decision-making, rather than simply predicting missing values in a static user-item interaction matrix.
Abstract
The paper argues that the current task formulation in recommender systems research often oversimplifies the problem by focusing on predicting missing values in a user-item interaction matrix, rather than capturing the dynamic and contextual nature of the user's decision-making process. The key insights are: Recommender systems should be viewed as dynamic processes that involve the user, the model, and the items, rather than a static prediction task. The user's decision-making is influenced by various contextual factors, which are often overlooked in academic research. Recommender tasks are inherently application-specific, as the factors influencing user decision-making vary across different scenarios. Defining research tasks based on specific application scenarios using domain-specific datasets may lead to more insightful findings. The mismatch between the inputs accessible to a model and the information available to users during their decision-making process is a key issue. Current datasets and evaluation protocols often fail to capture the necessary contextual information, leading to a disconnect between academic research and practical applications. Recommender systems should be conceptualized as a ranking problem that considers both the user's general preferences and their current decision-making context. A balanced approach is needed to effectively model the dynamic nature of user interactions. The paper concludes by emphasizing the need for more scenario-specific task formulations, compatible baselines, and evaluation settings that better simulate practical conditions, which will require the availability of high-quality datasets from real-world platforms.
Stats
"Recommender System is an attractive research area, evidenced by the increasing number of publications in the past two decades. Based on a prefix search of "recommend", about 5000 publications on RecSys were indexed on DBLP within the year 2023 alone." "simple baselines like nearest-neighbor outperform more advanced models" "the same few (and relatively old) datasets (i.e., MovieLens, Amazon review dataset) are used extensively" "older datasets may not be good proxies of the user behavior and preferences of today's users" "the majority of RecSys evaluations do not take global timeline into consideration when splitting a dataset into train and test sets"
Quotes
"there are no rigid guidelines that define a comprehensive list of essential baselines" "the algorithms do not generalize – the set of algorithms which perform well changes substantially across datasets and across performance metrics" "the heavy usage of the MovieLens dataset has also been noted in [Sun et al. 2023]" "older datasets may not be good proxies of the user behavior and preferences of today's users" "the majority of RecSys evaluations do not take global timeline into consideration when splitting a dataset into train and test sets"

Deeper Inquiries

How can we design recommender systems that better capture the dynamic and contextual nature of user decision-making, beyond the limitations of static user-item interaction matrices?

In order to design recommender systems that effectively capture the dynamic and contextual aspects of user decision-making, it is essential to move beyond the traditional static user-item interaction matrices. One approach is to incorporate temporal and contextual information into the recommendation process. This can be achieved by considering factors such as time of day, user location, user mood, and other contextual variables that influence user preferences at a given moment. Furthermore, the design of recommender systems should focus on understanding the decision-making process of users in real-time. This involves modeling the user's evolving interests and preferences during a session of interactions, rather than just predicting missing values in a static matrix. By incorporating the concept of user decision-making into the recommendation process, recommender systems can provide more personalized and relevant recommendations that align with the user's current needs and preferences. Additionally, recommender systems can leverage advanced techniques such as deep learning models, reinforcement learning, and contextual bandits to adapt to the dynamic nature of user interactions. These models can learn from user feedback in real-time and adjust recommendations based on the evolving context of the user's interactions.

How can the research community collaborate with industry partners to gain access to high-quality datasets that reflect the real-world complexities of recommender systems?

Collaboration between the research community and industry partners is crucial for gaining access to high-quality datasets that accurately reflect the complexities of real-world recommender systems. To facilitate this collaboration, researchers can engage with industry partners through joint research projects, data sharing agreements, and collaborative initiatives. One approach is to establish partnerships with companies that operate large-scale recommender systems, such as e-commerce platforms, streaming services, or social media platforms. By working closely with industry partners, researchers can gain access to proprietary datasets that contain rich and diverse information about user interactions, preferences, and contextual variables. Furthermore, researchers can collaborate with industry partners to design and conduct experiments that simulate real-world recommender system scenarios. By testing algorithms and models on industry-specific datasets, researchers can validate the effectiveness of their approaches in practical settings and ensure that their findings are applicable to real-world applications. Overall, fostering collaboration between the research community and industry partners is essential for accessing high-quality datasets, gaining insights into real-world recommender system challenges, and developing solutions that address the complexities of modern recommendation scenarios.

What are the potential challenges and trade-offs in moving towards more application-specific task formulations and evaluations in recommender systems research?

Moving towards more application-specific task formulations and evaluations in recommender systems research presents several challenges and trade-offs that researchers need to consider. One challenge is the increased complexity of designing task-specific models that cater to the unique requirements of different recommendation scenarios. Application-specific formulations may require specialized algorithms, data preprocessing techniques, and evaluation metrics, which can be resource-intensive and time-consuming to develop and implement. Another challenge is the generalizability of application-specific models across different domains or use cases. While task-specific models may excel in a particular application scenario, they may lack the flexibility to adapt to new environments or recommendation tasks. This trade-off between performance optimization for a specific use case and generalizability across diverse scenarios needs to be carefully balanced in research and development efforts. Furthermore, the availability of high-quality datasets that capture the nuances of specific recommendation scenarios can be a limiting factor in moving towards application-specific formulations. Researchers may face challenges in accessing real-world data that accurately reflects the complexities of user decision-making in different contexts, which can impact the validity and reliability of their findings. Overall, while application-specific task formulations and evaluations offer the potential for more tailored and effective recommender systems, researchers must navigate challenges related to complexity, generalizability, and data availability to ensure the success of their research endeavors.
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