Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty
Authors: Breznau Nate , Rinke Eike Mark , Wuttke Alexander , Nguyen Hung H. V. , Adem Muna , Adriaans Jule , Alvarez-Benjumea Amalia , Andersen Henrik K. , Auer Daniel , Azevedo Flavio , Bahnsen Oke , Balzer Dave , Bauer Gerrit , Bauer Paul C. , Baumann Markus , Baute Sharon , Benoit Verena , Bernauer Julian , Berning Carl , Berthold Anna , Bethke Felix S. , Biegert Thomas , Blinzler Katharina , Blumenberg Johannes N. , Bobzien Licia , Bohman Andrea , Bol Thijs , Bostic Amie , Brzozowska Zuzanna , Burgdorf Katharina , Burger Kaspar , Busch Kathrin B. , Carlos-Castillo Juan , Chan Nathan , Christmann Pablo , Connelly Roxanne , Czymara Christian S. , Damian Elena , Ecker Alejandro , Edelmann Achim , Eger Maureen A. , Ellerbrock Simon , Forke Anna , Forster Andrea , Gaasendam Chris , Gavras Konstantin , Gayle Vernon , Gessler Theresa , Gnambs Timo , Godefroidt Amélie , Grömping Max , Groß Martin , Gruber Stefan , Gummer Tobias , Hadjar Andreas , Heisig Jan Paul , Hellmeier Sebastian , Heyne Stefanie , Hirsch Magdalena , Hjerm Mikael , Hochman Oshrat , Hövermann Andreas , Hunger Sophia , Hunkler Christian , Huth Nora , Ignácz Zsófia S. , Jacobs Laura , Jacobsen Jannes , Jaeger Bastian , Jungkunz Sebastian , Jungmann Nils , Kauff Mathias , Kleinert Manuel , Klinger Julia , Kolb Jan-Philipp , Kołczyńska Marta , Kuk John , Kunißen Katharina , Kurti Sinatra Dafina , Langenkamp Alexander , Lersch Philipp M. , Löbel Lea-Maria , Lutscher Philipp , Mader Matthias , Madia Joan E. , Malancu Natalia , Maldonado Luis , Marahrens Helge , Martin Nicole , Martinez Paul , Mayerl Jochen , Mayorga Oscar J. , McManus Patricia , McWagner Kyle , Meeusen Cecil , Meierrieks Daniel , Mellon Jonathan , Merhout Friedolin , Merk Samuel , Meyer Daniel , Micheli Leticia , Mijs Jonathan , Moya Cristóbal , Neunhoeffer Marcel , Nüst Daniel , Nygård Olav , Ochsenfeld Fabian , Otte Gunnar , Pechenkina Anna O. , Prosser Christopher , Raes Louis , Ralston Kevin , Ramos Miguel R. , Roets Arne , Rogers Jonathan , Ropers Guido , Samuel Robin , Sand Gregor , Schachter Ariela , Schaeffer Merlin , Schieferdecker David , Schlueter Elmar , Schmidt Regine , Schmidt Katja M. , Schmidt-Catran Alexander , Schmiedeberg Claudia , Schneider Jürgen , Schoonvelde Martijn , Schulte-Cloos Julia , Schumann Sandy , Schunck Reinhard , Schupp Jürgen , Seuring Julian , Silber Henning , Sleegers Willem , Sonntag Nico , Staudt Alexander , Steiber Nadia , Steiner Nils , Sternberg Sebastian , Stiers Dieter , Stojmenovska Dragana , Storz Nora , Striessnig Erich , Stroppe Anne-Kathrin , Teltemann Janna , Tibajev Andrey , Tung Brian , Vagni Giacomo , Van Assche Jasper , van der Linden Meta , van der Noll Jolanda , Van Hootegem Arno , Vogtenhuber Stefan , Voicu Bogdan , Wagemans Fieke , Wehl Nadja , Werner Hannah , Wiernik Brenton M. , Winter Fabian , Wolf Christof , Yamada Yuki , Zhang Nan , Ziller Conrad , Zins Stefan , Żółtak Tomasz 
Published: October 2022

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.