Healthcare technologies are often appraised under considerable ambiguity over the size of incremental benefits and costs, and thus how decision-makers combine unclear information to make recommendations is of considerable public interest. This paper provides a conceptual foundation for such decision-making under ambiguity, formalizing and differentiating the decision problems of a representative policy-maker reviewing the results from an economic evaluation. A primary result is that presenting information to regulators in an incremental cost-effectiveness ratio or cost-effectiveness analysis (CEA) format instead of a net monetary benefit or cost–benefit analysis (CBA) framework may induce errors in decision-making when there exists ambiguity in incremental benefits and decision-makers use well-known decision rules to combine information. Ambiguity in incremental costs or the value of the cost-effectiveness threshold does not distort decision-making under these rules. In reasonable contexts, I show that the CEA framing may result in the approval of fewer technologies relative to CBA framing. I interpret these results as predictions on how the presentation of information from economic evaluations to regulators may frame and distort recommendations. All the results extend to non-healthcare contexts.

A BioBlitz is a rapid and intensive survey of a specific geographic area that brings together experts and often lay participants to assess biodiversity, typically of macrobiota that are easily observed and identifiable on-site. This concept has become popular across taxonomic fields, attracting interest globally to increase knowledge of local biodiversity. Inspired by the success of the approach, we undertook a ‘ParasiteBlitz’ at an unexplored locality (Stono Preserve, Charleston, South Carolina, USA) to determine its feasibility for parasites, whose assessment of diversity is largely neglected worldwide. We assembled a team of parasitologists with complementary expertise. Over 12 days (3 days in each habitat) in April 2023, we intensively screened fishes and aquatic invertebrates for parasites, and sampled sediment and water for environmental DNA (eDNA) metabarcoding from four aquatic habitats: wetland, freshwater pond, brackish impoundment, and tidal creek. We incorporated assistance from non-parasitologists and students. Details on methodologies and results are provided in individual papers in this Special Collection. Traditional methods revealed the presence of ca. 100 species of seven major metazoan parasite taxa, and the eDNA survey yielded over 1,000 amplicon sequence variants identified as parasites, most with sequences unmatched in GenBank, and resulting in only a few species identified as named species in the one-year post-Blitz timeframe we imposed upon ourselves for identification. Limitations and challenges of the ParasiteBlitz are discussed, and our results support that this approach can be effective for rapid discovery of the dimensions of parasite assemblages in an understudied environment and contribute to parasitology knowledge.

Households are frequently subject to income and asset shocks. We performed a lab experiment, inducing losses on a real effort task, after which we measured cognitive performance, loss aversion and cheating behavior. We found that asset losses, but not income losses, act as a cognitive load, by decreasing accuracy and increasing response times. We did not detect any change in dishonesty or loss aversion.

By means of a laboratory experiment, Rubin and Sheremeta (Manag Sci 62(4):985–999, 2016), study a bonus-version of the gift-exchange game, including two treatment variations. First they vary whether the effort provided by the agent directly translates into output for the principal, or whether it is distorted by a shock. Second, for the condition with a shock they vary whether the shock is observed by the principal, or not. The authors’ main findings are that (1) the introduction of an unobservable shock significantly reduces welfare; and (2) informing the principal about the size of the shock does not restore gift-exchange. In a replication study we largely reproduce finding (1), but we fail to confirm finding (2). Our data suggests that small behavioral differences in the initial rounds lead to a hysteresis effect that is responsible for the differences in results across studies.

We conduct a laboratory experiment to investigate the impact of deliberation time on behavior under risk and uncertainty. Towards this end we ask our participant to make quick, intuitive evaluations of a number of lotteries and report resulting certainty equivalents. Yet, we invite them to modify these initial decisions, whenever they find, after (additional) deliberation, that they do not precisely represent their preference. Both certainty equivalents are incentivized (a double-response method). The choice of evaluated lotteries allows us to semi-parametrically estimate the value function and the probability weighting function within the paradigm of the cumulative prospect theory. The main finding is that deliberation raises the probability weighting function (reduces pessimism), especially in the case of lotteries involving unknown probabilities.

Betrayal aversion has been operationalized as the evidence that subjects demand a higher risk premium to take social risks compared to natural risks. This evidence has been first shown by Bohnet and Zeckhauser (J Econ Behav 98:294–310, 2004) using an adaptation of the Becker–DeGroot–Marschak mechanism (BDM, Becker et al. Behav Sci 9:226–232, 1964). We compare their implementation of the BDM mechanism with a new version designed to facilitate subjects’ comprehension. We find that, although the two versions produce different distributions of values, the size of betrayal aversion, measured as an average treatment difference between social and natural risk settings, is not different across the two versions. We further show that our implementation is preferable to use in practice as it reduces substantially subjects’ mistakes and the likelihood of noisy valuations.

Since Holt and Laury (Am Econ Rev 92(5):1644–1655, 2002), the multiple price list (MPL) procedure has widely been used to elicit individual risk preferences. We assess the impact of varying list order and spacing, and of presentation via text or graphs. Relative to the original MPL baseline, some non-linear transformations of lottery prices systematically increase elicited risk aversion, while some graphical displays tend to reduce it.

It has been observed that, in a variety of tasks, losses have a larger impact on behavior than do gains of equal size. This phenomenon is referred to as loss aversion. It is thought that the negativity bias in behavior is reflected in and potentially causally related to a negativity bias in emotional arousal. We examine skin conductance responses—a psychophysiological marker for emotional arousal—during the anticipation of gains and losses. In contrast to most previous research, gains and losses were separated from each other and symmetric in magnitude. We found that skin conductance responses during the anticipation phase increased with the magnitude of both gains and losses. Contrary to the predictions of the loss aversion hypothesis, the anticipation of a loss did not elicit stronger reactions than the anticipation of a gain of equal size.

This paper examines cooperation and punishment in a public goods game in Istanbul. Unlike prior within-subject designs, we use a between-subject design with separate no-punishment and punishment conditions. This approach reveals that punishment significantly increases contributions, demonstrating the detrimental effect of having prior experience without sanctions. We highlight two critical factors—heterogeneous initial contributions across groups and how subjects update their contributions based on prior contributions and received punishment. An agent-based model verifies that the interaction between these two factors leads to a strong persistence of contributions over time. Analysis of related data from comparable cities shows similar patterns, suggesting our findings likely generalize if using a between-subject design. We conclude that overlooking within-group heterogeneity biases cross-society comparisons and subsequent policy implications.

We compare different implementations of the Stochastic Becker–DeGroot–Marschak (SBDM) belief elicitation mechanism, which is theoretically elegant but challenging to implement. In a first experiment, we compare three common formats of the mechanism in terms of speed and data quality. We find that all formats yield reports with similar levels of accuracy and precision, but that the instructions and reporting format adapted from Hao and Houser (J Risk Uncertain 44(2):161–180 2012) is significantly faster to implement. We use this format in a second experiment in which we vary the delivery method and quiz procedure. Dropping the pre-experiment quiz significantly compromises the accuracy of subject’s reports and leads to a dramatic spike in boundary reports. However, switching between electronic and paper-based instructions and quizzes does not affect the accuracy or precision of subjects’ reports.

I find necessary and sufficient conditions for first-order stochastic dominance (FOSD) violations for choices from a budget line of Arrow securities. Applying this characterization to existing data, I compare FOSD violation rates across a broad set of risk preference elicitation tasks.

We convey our experiences developing and implementing an online experiment to elicit subjective beliefs and economic preferences. The COVID-19 pandemic and associated closures of our laboratories required us to conduct an online experiment in order to collect beliefs and preferences associated with the pandemic in a timely manner. Since we had not previously conducted a similar multi-wave online experiment, we faced design and implementation considerations that are not present when running a typical laboratory experiment. By discussing these details more fully, we hope to contribute to the online experiment methodology literature at a time when many other researchers may be considering conducting an online experiment for the first time. We focus primarily on methodology; in a complementary study we focus on initial research findings.

For simple prospects routinely used for certainty equivalent elicitation, random expected utility preferences imply a conditional expectation function that can mimic deterministic rank-dependent preferences. That is, a subject with random expected utility preferences can have expected certainty equivalents exactly like those predicted by rank-dependent probability weighting functions of the inverse-s shape discussed by Quiggin (J Econ Behav Organ 3:323–343, 1982) and advocated by Tversky and Kahneman (J Risk Uncertainty 5:297–323, 1992), Prelec (Econometrica 66:497–527, 1998) and other scholars. Certainty equivalents may not nonparametrically identify preferences: Their conditional expectation (and critically, their interpretation) depends on assumptions concerning the source of their variability.

We examine the ability of eye movement data to help understand the determinants of decision-making over risky prospects. We start with structural models of choice under risk, and use that structure to inform what we identify from the use of process data in addition to choice data. We find that information on eye movements does significantly affect the extent and nature of probability weighting behavior. Our structural model allows us to show the pathway of the effect, rather than simply identifying a reduced form effect. This insight should be of importance for the normative design of choice mechanisms for risky products. We also show that decision-response duration is no substitute for the richer information provided by eye-tracking.

The high rewards people desire are often unlikely. Here, we investigated whether decision-makers exploit such ecological correlations between risks and rewards to simplify their information processing. In a learning phase, participants were exposed to options in which risks and rewards were negatively correlated, positively correlated, or uncorrelated. In a subsequent risky choice task, where the emphasis was on making either a ‘fast’ or the ‘best’ possible choice, participants’ eye movements were tracked. The changes in the number, distribution, and direction of eye fixations in ‘fast’ trials did not differ between the risk–reward conditions. In ‘best’ trials, however, participants in the negatively correlated condition lowered their evidence threshold, responded faster, and deviated from expected value maximization more than in the other risk–reward conditions. The results underscore how conclusions about people’s cognitive processing in risky choice can depend on risk–reward structures, an often neglected environmental property.

We study how Spanish equity investors assessed firms’ exposure to political risk during the regime change of the 1930s. We show that shifts in political uncertainty regularly predicted a general deterioration of future investment opportunities in the stock market. However, we also find that firms differed in their sensitivity to uncertainty, reflecting important differences in their perceived exposures to political risk. The negative impact of uncertainty was significantly milder for firms with political connections to republican parties. The price of some stocks increased in periods of heightened uncertainty, thus allowing investors to hedge against reinvestment risk. In the case of firms that became targets of hostile political actions, we observe that investors frequently adjusted their assessment of individual stocks to changes in firm-specific political circumstances. Over the whole period of the Second Republic, investors' systematic preference for safer equity hedges led to a continuous decline in the price of stocks perceived as more exposed to political risk.

We experimentally study how mutual payoff information affects strategic play. Subjects play the Prisoner's Dilemma or Stag Hunt game against randomly re-matched opponents under two information treatments. In our partial-information treatment, subjects are shown only their own payoff structure, while in our full-information treatment they are shown both their own and their opponent's payoff structure. In both treatments, they receive feedback on their opponent's action after each round. We find that mutual payoff information initially facilitates reaching the socially optimal outcome in both games. Play in the Prisoner's Dilemma converges toward the unique Nash equilibrium of the game under both information treatments, while in the Stag Hunt mutual payoff information has a substantial impact on play and equilibrium selection in all rounds of the game. Belief-learning model estimations and simulations suggest these effects are driven by both initial play and the way subjects learn.

This paper investigates risk preferences using an artefactual field experiment conducted with a non-standard subject pool of farmers in Ghana. I introduce an alternative methodology for studying preferences following replication of a seminal risk elicitation procedure by Binswanger (Am J Agric Econ 62(3):395407, 1980). An important feature of both approaches is that they are easy to understand and, hence, are particularly suitable for eliciting preferences among subjects with low levels of formal education. I successfully replicate Binswanger's study, documenting how his original result of the moderate level of risk aversion for an average farmer can be generalized to a different country. However, using my alternative approach, whereby lotteries are presented in the loss domain, I find that half of my experimental subjects violated expected utility theory. This approach is of relevance to the current literature on studying risk preferences among subjects with poor literacy skills.

Salience theory relies on the assumption that not only the marginal distribution of lotteries, but also the correlation of payoffs across states impacts choices. Recent experimental studies on salience theory seem to provide evidence in favor of such correlation effects. However, these studies fail to control for event-splitting effects (ESE). In this paper, we seek to disentangle the role of correlation and event-splitting in two settings: (1) the common consequence Allais paradox as studied by Bordalo et al. (Q J Econ 127:1243–1285, 2012), Frydman and Mormann (The role of salience in choice under risk: An experimental investigation. Working Paper, 2018), and Bruhin et al. (J Risk Uncertain 65:139–184, 2022); (2) choices between Mao pairs as studied by Dertwinkel-Kalt and Köster (J Eur Econ Assoc 18:2057–2107, 2020). In both settings, we find evidence suggesting that recent findings supporting correlation effects are largely driven by ESE. Once controlling for ESE, we find no consistent evidence for correlation effects. Our results thus shed doubt on the validity of salience theory in describing risky behavior.

Decision makers typically possess limited knowledge on states of the world so that use of information from past similar experiences is reasonable. This analogical thinking is formalised by case-based decision theory (CBDT). We created a novel experimental setting to validate the predictive power of CBDT versus Bayesian reasoning. Participants encountered a salient but irrelevant cue which a Bayesian decision maker is likely to ignore but a case-based decision maker may use in assessing similarity. We find that although the irrelevant similarity cue was used, the pattern in participants’ decisions is neither case-based nor Bayesian. The results suggest that CBDT does not apply in simple decision settings where similarity cues are uninformative.