Incentive-aligned Conjoint Analysis

Because most conjoint studies are conducted in hypothetical situations with no consumption consequences for the participants, the extent to which the studies are able to uncover "true" consumer preference structures is questionable. Experimental economics literature, with its emphasis on incentive alignment and hypothetical bias, suggests that more realistic incentivealigned studies will result in stronger out-of-sample predictive performance of actual purchase behaviors and provide better estimates of consumer preference structures than hypothetical studies. To test this hypothesis, the authors design an experiment with conventional (hypothetical) conditions and their parallel incentive-aligned counterparts. Using Chinese dinner specials as the context, the authors conducted a field experiment in a Chinese restaurant during dinnertime. The results provide strong evidence in favor of incentive-aligned choice conjoint analysis, in that incentive-aligned choice conjoint outperforms hypothetical choice conjoint in out-of-sample predictions (59% versus 26% for incentive-aligned choice conjoint and hypothetical choice conjoint, respectively for the top two choices). As expected, subjects in the incentive-aligned choice condition exhibit preference structures that are systematically different from the preference structures of subjects in the hypothetical condition. Most notably, the subjects in the incentive-aligned choice condition are more price sensitive and exhibit different heterogeneity patterns. To determine the robustness of these results, the authors conducted a second study that used snacks as the context and only considered the choice treatments. This study confirmed the results by again providing strong evidence in favor of incentive-aligned choice analysis in out-of-sample predictions (36% versus 16% for incentive-aligned choice conjoint and hypothetical choice conjoint, respectively for the top two choices). The results provide a strong motivation for conjoint practitioners to consider conducting their studies in realistic settings using incentive structures that require participants to æ–—ive with?their decisions.

Internal or external magma oceans in the earliest protoplanets -- perspectives from nitrogen and carbon fractionation

When the extent of protoplanetary melting approached magma ocean (MO)-like conditions, alloy melts efficiently segregated from the silicates to form metallic cores. The nature of the MO of a differentiating protoplanet, i.e., internal or external MO (IMO or EMO), not only determines the abundances of life-essential volatiles like nitrogen (N) and carbon (C) in its core and mantle reservoirs but also the timing and mechanism of volatile loss. Whether the earliest formed protoplanets had IMOs or EMOs is, however, poorly understood. Here we model equilibrium N and C partitioning between alloy and silicate melts in the absence (IMO) or presence (EMO) of vapor degassed atmospheres. Bulk N and C inventories of the protoplanets during core formation are constrained for IMOs and EMOs by comparing the predicted N and C abundances in the alloy melts from both scenarios with N and C concentrations in the parent cores of magmatic iron meteorites. Our results show that in comparison to EMOs, protoplanets having IMOs satisfy N and C contents of the parent cores with substantially lower amounts of bulk N and C present in the parent body during core formation. As the required bulk N and C contents for IMOs and EMOs are in the sub-chondritic and chondritic range, respectively, N and C fractionation models alone cannot be used to distinguish the prevalence of these two end-member differentiation regimes. A comparison of N and C abundances in chondrites with their peak metamorphic temperatures suggests that protoplanetary interiors could lose a substantial portion of their N and C inventories with increasing degrees of thermal metamorphism.Comment: 19 pages, 8 figures, 1 tabl

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Efficacy of epidural steroid injections in treatment of lumbar spinal stenosis

Epidural steroid injections (ESI) are used as a conservative therapy for treating lumbar spinal stenosis (LSS), yet there is no concrete justification for them. Data from a randomized control trial evaluating the effectiveness of ESI in LSS patients was analyzed. Main outcomes were measured by French-translated LSS symptom severity, physical function, and satisfaction scales over 3 months. The first stage of the analyses evaluated psychometric properties of the scales and showed high internal consistency and test-retest reliability. The main analyses addressed ESI efficacy. Repeated measures analysis of variance over the first 3 months showed a marginally statistically significant improvement in symptom severity, physical function, and satisfaction in the ESI group, compared to placebo. Treatment effectiveness tended to decrease over time. Differences between groups were not significant at 6 and 12 months. All scales had a significant interaction between treatment and high blood pressure (HBP): subjects without HBP responded substantially better