Mechanisms for Making Accurate Decisions in Biased Crowds

Abstract This paper studies procedures for identifying the true answer to a binary question using the opinions of potentially-biased individuals. It's common and natural to side with the majority opinion, but the majority may make the wrong choice when the agents are biased. Taking majority rule as a baseline, I study peer-prediction decision rules, which ask agents to predict the opinions of others in addition to providing their own. This extra information enables us to potentially recognize the correct answer even when the majority is wrong. I first show that peer-prediction rules cannot be more accurate than the majority when we require them to satisfy the same symmetry conditions as majority rule and to be incentive-compatible for agents who intend to push the final decision towards their own opinion. Realistically though, not all agents distort their information strategically. I provide a simple decision rule based on the median agent's prediction that matches majority rule when all agents are strategic and makes more accurate decisions than majority rule when some agents are honest

Incentive-Compatible Inference from Subjective Opinions Without Common Belief Systems

Abstract. Peer-prediction mechanisms elicit information about unverifiable or subjective states of the world. Existing mechanisms in the class are designed so participants maximize their expected payments when reporting honestly. However, these mechanisms do not account for participants desiring influence over how reports are used. When participants want the conclusions drawn from reports to reflect their own opinion, the inference procedure must be subjected to incentive-compatibility constraints to ensure honesty. In this paper, I develop mechanisms without payments for discerning the true answer to a binary question, even in the presence of a false consensus. I first characterize all continuous, neutral, and anonymous mechanisms in this setting that can be implemented in interimrationalizable strategies. Using this representation, I optimize across the class of mechanisms for accuracy in distinguishing the true state. Because the mechanism does not require knowledge of the distribution of agent types and is neutral between both outcomes, it can serve as a test for bias in the surveyed population

Essays in information elicitation and market design

This dissertation consists of three essays in microeconomic theory. The first two focus on how to elicit information about the state of the world from strategic agents, either to make a decision or for its own sake. The third studies a model of decentralized two-sided matching markets. In "Mechanisms for making accurate decisions in biased crowds," I study decision rules for finding the true answer to a binary question using the opinions of biased agents. Taking majority rule as a baseline, I study peer-prediction decision rules, which ask agents to predict the opinions of others in addition to providing their own. Incorporating first-order beliefs into the decision rule has the potential to recognize the correct answer even when the majority is wrong. However, I show the majority rule is essentially the only deterministic, neutral, anonymous, and interim dominance solvable mechanism. I then characterize all randomized peer-prediction mechanisms with these properties, using this result to show majority rule is the optimal mechanism in this class. Finally, I consider a simple, non-incentive-compatible decision rule based on the median prediction that implements majority rule when all agents are strategic and improves on majority rule when an unknown subpopulation is honest. In "Minimum truth serums with optional predictions," I introduce a class of mechanisms for eliciting private correlated signals from a group of expected score maximizers without external verification or knowledge about the agents' belief structure. Built on proper scoring rules, these minimum truth serums ask agents to report a signal and a prediction of the signals of others. If two agents with the same signal have the same expectations about the signals of others, the Bayesian incentive compatibility of these mechanisms follows with no further assumptions on the agents' belief structure. With a slight modification, the mechanism is still feasible and incentive compatible when the prediction portion of the report is optional. In "Uncoordinated two-sided matching markets," I study a decentralized proposal model in joint work with Juan Fung. The study of two-sided matching markets is now a major subfield of market design, focused primarily on the variants of the deferred acceptance algorithm. As a centralized mechanism, deferred acceptance is guaranteed to return a stable match. However, there is little definite work on whether uncoordinated agents find a stable matching on their own and the consequences if not. We show that small to moderately large uncoordinated markets reach a stable match within n^2 proposals from each agent when the proposal strategy isn't completely naive. We also show that stopping the proposal process early before stabilizing results in a more egalitarian and higher welfare match, particular when the two sides of the market are unbalanced. This suggests uncoordinated markets wouldn't benefit from centralization unless there is an obvious failing like market unraveling

Grand Movement: Influence of Fitness Sessions on Static and Dynamic Balance in Older Adults

It is recommended that adults 65 years and older engage in activities to improve balance such as standing on one foot at least 3 days a week (CDC, 2022). Flexibility and balance are vital components of fitness for older adults in order to perform activities of daily living (ADLs) and aid in reducing risk of falling which is prevalent in senior living facilities. Fear of falling is a belief that an individual cannot prevent themselves from falling or that they have a nagging worry that they will fall (Varshneya & Sonawane, 2020). PURPOSE: To evaluate static and dynamic balance, static flexibility and reaction time in two older adult populations (fitness session group vs non-fitness session group). METHODS: Participants (n=31) were recruited within a senior living facility and completed a physical activity (PA) questionnaire to be placed into appropriate groups. Fitness session group participants were encouraged to maintain activity levels as identified by the PA questionnaire. Pre and post measurements were assessed 6-8 weeks apart. Assessments included Back Saver Sit and Reach (R/L), Standard Romberg (eyes open and closed), Standing Functional Reach, 5 Time Sit to Stand, and Timed Up and Go. RESULTS: In the Standing Functional Reach significant differences were found in the Session x Group Interaction (F(1,28)=4.455, p=0.044) (np2=0.137), as well as the pre to post assessment comparisons (F(1,28)=6.760, p=0.015) (np2=0.194). Significant results were also found on the 5 Time Sit to Stand in the pre to posttest analysis (F(1,23)=7.813, p=0.010)(np2=0.254), as well as the between groups analysis (F(1,3)=8.906, p=0.007)(np2=0.279). Significant differences were also found in the Group x Session interaction for the Timed Up and Go (F(1,26)=6.905, p=0.014)(np2=0.210). CONCLUSION: The Fitness Session Group improved measurements on all 7 assessments (except Romberg with eyes open), and exhibited higher averages than the Non-Fitness Session Group. There is evident benefit to assisted and independent living facilities providing fitness programming and encouraging physical activity within the older adult population. These resources help reduce the risk of injury and enhance quality of life

Senior Recital

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Surveillance of low pathogenic novel H7N9 avian influenza in commercial poultry barns: detection of outbreaks and estimation of virus introduction time

Background Both high and low pathogenic subtype A avian influenza remain ongoing threats to the commercial poultry industry globally. The emergence of a novel low pathogenic H7N9 lineage in China presents itself as a new concern to both human and animal health and may necessitate additional surveillance in commercial poultry operations in affected regions. Methods Sampling data was simulated using a mechanistic model of H7N9 influenza transmission within commercial poultry barns together with a stochastic observation process. Parameters were estimated using maximum likelihood. We assessed the probability of detecting an outbreak at time of slaughter using both real-time polymerase chain reaction (rt-PCR) and a hemagglutinin inhibition assay (HI assay) before considering more intense sampling prior to slaughter. The day of virus introduction and R 0 were estimated jointly from weekly flock sampling data. For scenarios where R 0 was known, we estimated the day of virus introduction into a barn under different sampling frequencies. Results If birds were tested at time of slaughter, there was a higher probability of detecting evidence of an outbreak using an HI assay compared to rt-PCR, except when the virus was introduced <2 weeks before time of slaughter. Prior to the initial detection of infection N s a m p l e = 50 (1%) of birds were sampled on a weekly basis once, but after infection was detected, N s a m p l e = 2000 birds (40%) were sampled to estimate both parameters. We accurately estimated the day of virus introduction in isolation with weekly and 2-weekly sampling. Conclusions A strong sampling effort would be required to infer both the day of virus introduction and R 0. Such a sampling effort would not be required to estimate the day of virus introduction alone once R 0 was known, and sampling N s a m p l e = 50 of birds in the flock on a weekly or 2 weekly basis would be sufficient

Senior Recital

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Sedation and Acute Encephalopathy in a Pediatric Patient Following Ingestion of Delta-8-Tetrahydrocannabinol Gummies

BACKGROUND Delta-8 tetrahydrocannabinol (delta-8 THC) is an isomer of delta-9-tetrahydrocannabinol (delta-9 THC), the primary psychoactive cannabinoid in the marijuana plant. Typically found at lower concentrations in marijuana, delta-8 THC exhibits psychoactive properties similar to delta-9 THC. Products containing delta-8 THC are readily available across the US and currently there is a lack of available confirmatory testing specific to delta-8 THC as there is cross-reactivity to other naturally occurring cannabinoids in standard immunoassays. Pediatric exposures to this substance are on the rise. CASE REPORT We present a case with laboratory confirmation of a previously healthy 2-year-old girl ingesting approximately 15 mg/kg of delta-8 THC gummies. The patient arrived minimally responsive and requiring intubation for encephalopathy. Laboratory confirmation of delta-8 THC exposure is not routinely available with common testing modalities. A urine drug screen preformed in the hospital was positive for delta-9 THC. With the collaboration of the Drug Enforcement Administration\u27s Toxicology Testing Program, detection and confirmation of delta-8 THC was performed in the serum and urine using liquid chromatography-quadrupole time-of-flight mass spectrometry. CONCLUSIONS The prevalence of delta-8 THC-containing products in the illicit drug market is increasing rapidly. Delta-8 THC products are now available in gas stations and in headshops. The clinical presentation of delta-8 THC exposure is similar to known effects of delta-9 THC exposure. These similarities limit the clinicians\u27 abilities to determine the specific substance ingested. Symptomatic and supportive care remains an effective treatment for cannabinoid toxicity