Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty.

This study explores how researchers' analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers' expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each team's workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers' results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.

The pleasure principle Why (some) people develop a taste for politics: Evidence from a preregistered experiment.

Existing theories struggle when political engagement is an end in itself. To explain intrinsically motivated engagement in politics, this study synthesizes psychological theories to deduce a need-based theory of political motivation. It posits that intrinsic political motivation has roots in seemingly apolitical processes of need satisfaction that are universal and deeply ingrained in the human psyche. However, in a high-powered survey experiment, 14 of 15 preregistered analytical tests did not yield the expected evidence for the basic tenet that previous need-related experiences with politics affect the quality and quantity of future activities in the political domain. Showcasing a stepwise approach to engage with null results in hypothesis-driven research, post hoc analyses solidify the null findings, which call into question the validity of the presented theory and the previous evidence on which it was built. This study thus enhances our understanding of what does and does not underlie intrinsic motivation for political engagement.