Publications by IORA

Zixin Zhong, Wang Chi Cheung, Vincent Y. F. Tan
Motivated by the pressing need for efficient optimization in online recommender systems, we revisit the cascading bandit model proposed by Kveton et al. (2015). While Thompson sampling (TS) algorithms have been shown to be empirically superior to Upper Confidence Bound (UCB) algorithms for cascading bandits, theoretical guarantees are only…
Z Journal of Machine Learning Research, Vol. 22, No. 218, Pages 1 – 66, 2021
Zixin Zhong, Wang Chi Cheung, Vincent Y. F. Tan
Motivated by the pressing need for efficient optimization in online recommender systems, we revisit the cascading bandit model proposed by Kveton et al. (2015). While Thompson sampling (TS) algorithms have been shown to be empirically superior to Upper Confidence Bound (UCB) algorithms for cascading bandits, theoretical guarantees are only…
Z Journal of Machine Learning Research, Vol. 22, No. 218, Pages 1 – 66, 2021
John R. Birge , Yifan Feng , N. Bora Keskin , Adam Schultz
We study the profit maximization problem of a market maker in a spread betting market. In this market, the market maker quotes cutoff lines for the outcome of a certain future event as “prices,” and bettors bet on whether the event outcome exceeds the cutoff lines. Anonymous bettors with…
Operations Research
John R. Birge , Yifan Feng , N. Bora Keskin , Adam Schultz
We study the profit maximization problem of a market maker in a spread betting market. In this market, the market maker quotes cutoff lines for the outcome of a certain future event as “prices,” and bettors bet on whether the event outcome exceeds the cutoff lines. Anonymous bettors with…
Operations Research
Yifan Feng , René Caldentey , Christopher Thomas Ryan
This paper studies a class of ranking and selection problems faced by a company that wants to identify the most preferred product out of a finite set of alternatives when consumer preferences are a priori unknown. The only information available is that consumer preferences satisfy two key properties: (i)…
Operations Research
Yifan Feng , René Caldentey , Christopher Thomas Ryan
This paper studies a class of ranking and selection problems faced by a company that wants to identify the most preferred product out of a finite set of alternatives when consumer preferences are a priori unknown. The only information available is that consumer preferences satisfy two key properties: (i)…
Operations Research
Jussi Keppo, A. Max Reppen, H. Mete Soner
We propose a model in which dividend payments occur at regular, deterministic intervals in an otherwise continuous model. This contrasts traditional models where either the payment of continuous dividends is controlled or the dynamics are given by discrete time processes. Moreover, between two dividend payments, the structure allows for…
Partly supported by the ETH Foundation, the Swiss Finance Institute, and Swiss National Foundation grant SNF 200020_172815.
Mathematics of Operations Research
Jussi Keppo, A. Max Reppen, H. Mete Soner
We propose a model in which dividend payments occur at regular, deterministic intervals in an otherwise continuous model. This contrasts traditional models where either the payment of continuous dividends is controlled or the dynamics are given by discrete time processes. Moreover, between two dividend payments, the structure allows for…
Mathematics of Operations Research
Partly supported by the ETH Foundation, the Swiss Finance Institute, and Swiss National Foundation grant SNF 200020_172815.
Jussi Keppo, Tyler Shumway, Daniel Weagley
We document significant persistence in the market timing performance of active individual investors, suggesting that some investors are skilled at timing. Using data on all trades by active Finnish individual investors over almost 15 years, we also show that the net purchases of skilled versus unskilled investors predict monthly…
The Review of Asset Pricing Studies
Jussi Keppo, Tyler Shumway, Daniel Weagley
We document significant persistence in the market timing performance of active individual investors, suggesting that some investors are skilled at timing. Using data on all trades by active Finnish individual investors over almost 15 years, we also show that the net purchases of skilled versus unskilled investors predict monthly…
The Review of Asset Pricing Studies
Sumit Agarwal, Ben Charoenwong, Shih-Fen Cheng, Jussi Keppo
We study the role of ride-hailing surge factors on the allocative efficiency of taxis by combining a reduced-form estimation with structural analyses using machine-learning-based demand predictions. Where other research study the effect of entry on incumbent taxis, we use higher frequency granular data to study how location-time-specific surge factors…
Transportation Research Part C: Emerging Technologies
Sumit Agarwal, Ben Charoenwong, Shih-Fen Cheng, Jussi Keppo
We study the role of ride-hailing surge factors on the allocative efficiency of taxis by combining a reduced-form estimation with structural analyses using machine-learning-based demand predictions. Where other research study the effect of entry on incumbent taxis, we use higher frequency granular data to study how location-time-specific surge factors…
Transportation Research Part C: Emerging Technologies
Jussi Keppo, Michael Jong Kim, Xinyuan Zhang Sauder
We study optimal manipulation of a Bayesian learner through adaptive provisioning of information. The problem is motivated by settings in which a firm can disseminate possibly biased information at a cost, to influence the public’s belief about a hidden parameter related to the firm’s payoffs. For example, firms advertise…
Operations research
Jussi Keppo, Michael Jong Kim, Xinyuan Zhang Sauder
We study optimal manipulation of a Bayesian learner through adaptive provisioning of information. The problem is motivated by settings in which a firm can disseminate possibly biased information at a cost, to influence the public’s belief about a hidden parameter related to the firm’s payoffs. For example, firms advertise…
Operations research
Yanwei Jia, Jussi Keppo, Ville Satopää
Decision makers often ask experts to forecast a future state. Experts, however, can be biased. In the economics and psychology literature, one extensively studied behavioral bias is called herding. Under strong levels of herding, disclosure of public information may lower forecasting accuracy. This result, however, has been derived only…
Management Science
Yanwei Jia, Jussi Keppo, Ville Satopää
Decision makers often ask experts to forecast a future state. Experts, however, can be biased. In the economics and psychology literature, one extensively studied behavioral bias is called herding. Under strong levels of herding, disclosure of public information may lower forecasting accuracy. This result, however, has been derived only…
Management Science
Daniel Zhuoyu Long, Melvyn Sim, Minglong Zhou
We present a general framework for data-driven optimization called robustness optimization that favors solutions for which a risk-aware objective function would best attain an acceptable target even when the actual probability distribution deviates from the empirical distribution. Unlike robust optimization approaches, the decision maker does not have to size…
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Operations Research
Daniel Zhuoyu Long, Melvyn Sim, Minglong Zhou
We present a general framework for data-driven optimization called robustness optimization that favors solutions for which a risk-aware objective function would best attain an acceptable target even when the actual probability distribution deviates from the empirical distribution. Unlike robust optimization approaches, the decision maker does not have to size…
Operations Research
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Xiaobo Li, Hailong Sun, Chung-Piaw Teo
We study the bundle size pricing (BSP) problem where a monopolist sells bundles of products to customers, and the price of each bundle depends only on the size (number of items) of the bundle. Although this pricing mechanism is attractive in practice, finding optimal bundle prices is difficult since…
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Management Science
Xiaobo Li, Hailong Sun, Chung-Piaw Teo
We study the bundle size pricing (BSP) problem where a monopolist sells bundles of products to customers, and the price of each bundle depends only on the size (number of items) of the bundle. Although this pricing mechanism is attractive in practice, finding optimal bundle prices is difficult since…
Management Science
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Guodong Lyu, Chung-Piaw Teo
Problem Definition: The Singapore government has recently proposed the concept of “Locker Alliance” (LA), an interoperable network of public lockers in residential areas and hot spots in community, to improve the efficiency of last mile parcel delivery operations. This is to complement the existing infrastructure, comprising mainly of proprietary…
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Guodong Lyu, Chung-Piaw Teo
Problem Definition: The Singapore government has recently proposed the concept of “Locker Alliance” (LA), an interoperable network of public lockers in residential areas and hot spots in community, to improve the efficiency of last mile parcel delivery operations. This is to complement the existing infrastructure, comprising mainly of proprietary…
MSOM
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Najakorn Khajonchotpanya, Yilin Xue, Napat Rujeerapaiboon
We study multi-armed bandit problems that use conditional value-at-risk as an underlying risk measure. In particular, we propose a new upper confidence bound algorithm and compare it with the state-of-the-art alternatives with respect to various definitions of regret from the risk-averse online learning literature. For each comparison, we demonstrate…
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)
Operations Research Letters
Najakorn Khajonchotpanya, Yilin Xue, Napat Rujeerapaiboon
We study multi-armed bandit problems that use conditional value-at-risk as an underlying risk measure. In particular, we propose a new upper confidence bound algorithm and compare it with the state-of-the-art alternatives with respect to various definitions of regret from the risk-averse online learning literature. For each comparison, we demonstrate…
Operations Research Letters
This research is supported by the Ministry of Education, Singapore, under its 2019 Academic Research Fund Tier 3 grant call (Award ref: MOE-2019-T3-1-010)