P-hacking in Clinical Trials: A Meta-Analytical Approach

Clinical trials play a decisive role in the drug approval processes. By completing a p-curve analysis of a newly compiled data set that consists of thousands of clinical trials, we substantiate that the occurrence of p-hacking in clinical trials is not merely hypothetical. Medical and pharmaceutical research consists of both primary and secondary study endpoints. The primary finding covers the main effect, which directly influences the approval process, while the secondary outcome delivers further additional information. For primary p-curves, we observed an abnormal increase in the p-value frequency at common significance thresholds, while the secondary p-curves exhibited no such anomaly

Acute tryptophan depletion in healthy subjects increases preferences for negative reciprocity.

Reciprocity motivates to reward those who are kind (= positive reciprocity) and to punish those who are unkind (= negative reciprocity). The neurotransmitter serotonin (5-HT) modulates human behavior in numerous social situations, such as retaliation in response to perceived unfairness. In a placebo-controlled study, we used acute tryptophan depletion (ATD) to investigate the influence of available serotonin on choice behavior and reciprocity in the Hawk-Dove game. This game illustrates a conflict situation and incorporates two potential strategies: the cooperative Dove strategy and the uncooperative, more aggressive Hawk strategy. After strategic choices, we elicited the subjects' expectations (= beliefs) regarding the opponent's choices and controlled for risk preferences and current mood. We defined strategy choices as negative reciprocity when the participants opted for Hawk in response to an expected Hawk. We hypothesized that the ATD-induced reduction of 5-HT availability would increase participants' preferences for negative reciprocity. Generalized estimating equations reveal no significant main effect of ATD on assessed belief, mood, or risk attitude. But assessment of ATD's marginal effects over beliefs suggests that ATD significantly increases the tendency for negative reciprocity, whereas positive reciprocity (Dove in response to an expected Dove) is unaffected. We could therefore demonstrate that 5-HT availability mediates (negative) reciprocal behavior in social decision-making

Crossing incentive alignment and adaptive designs in choice-based conjoint: A fruitful endeavor

Choice-based conjoint (CBC) analysis is one of the most widely applied market research techniques. This study focuses on two principles that seek to enhance CBC: incentive alignment and adaptive choice-based conjoint (ACBC) analysis. Individually, these principles have proven to increase the forecasting accuracy of CBC, however there is a lack of research considering both principles simultaneously. Drawing on two lab and two online experiments, the present study fills this gap, and tests whether combining both principles yields superior results. On the one hand, the findings reveal that incentive-aligned CBC and hypothetical ACBC predict comparatively well. On the other hand, ACBC proposes a more efficient cost-per-information ratio in studies with a high sample size. Moreover, the newly introduced incentive-aligned ACBC achieves the best predictions. Based on our studies, we help market researchers to decide whether to apply incentive alignment, ACBC, or both, depending on the context of a specific application