Observing Many Researchers Using the Same Data and Hypothesis Reveals a Hidden Universe of Uncertainty
Authors: Breznau Nate , Rinke Eike Mark , Wuttke Alexander , Adem Muna , Adriaans Jule , Alvarez-Benjumea Amalia , Andersen Henrik Kenneth , Auer Daniel , Azevedo Flavio , Bahnsen Oke , Balzer Dave , Bauer Gerrit , Bauer Paul , Baumann Markus , Baute Sharon , Benoit Verena , Bernauer Julian , Berning Carl , Berthold Anna , Bethke Felix S. , Biegert Thomas , Blinzler Katharina , Blumenberg Johannes , Bobzien Licia , Bohman Andrea , Bol Thijs , Bostic Amie , Brzozowska Zuzanna , Burgdorf Katharina , Burger Kaspar , Busch Kathrin , Castillo Juan Carlos , Chan Nathan , Christmann Pablo , Connelly Roxanne , Czymara Christian S. , Damian Elena , Ecker Alejandro , Edelmann Achim , Eger Maureen A. , Ellerbrock Simon , Forke Anna , Forster Andrea Gabriele , 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-Stöckle Nora , Ignacz Zsofia , Jacobs Laura , Jacobsen Jannes , Jaeger Bastian , Jungkunz Sebastian , Jungmann Nils , Kauff Mathias , Kleinert Manuel , Klinger Julia , Kolb Jan-Philipp , Kołczyńska Marta , Kuk John Seungmin , Kunißen Katharina , Sinatra Dafina Kurti , Greinert Alexander , Lersch Philipp M. , Löbel Lea-Maria , Lutscher Philipp , Mader Matthias , Madia Joan Eliel , Malancu Natalia , Maldonado Luis , Marahrens Helge , Martin Nicole , Martinez Paul , Mayerl Jochen , MAYORGA OSCAR Jose , McManus Patricia A. , Wagner Kyle , Meeusen Cecil , Meierrieks Daniel , Mellon Jonathan , Merhout Friedolin , Merk Samuel , Meyer Daniel , Micheli Leticia , Mijs Jonathan J.B. , Moya Cristóbal , Neunhoeffer Marcel , Nüst Daniel , Nygård Olav , Ochsenfeld Fabian , Otte Gunnar , Pechenkina Anna , Prosser Christopher , Raes Louis , Ralston Kevin , Ramos Miguel , Roets Arne , Rogers Jonathan , Ropers Guido , Samuel Robin , Sand Gergor , Schachter Ariela , Schaeffer Merlin , Schieferdecker David , Schlueter Elmar , Schmidt Katja , Schmidt Regine , Schmidt-Catran Alexander , Schmiedeberg Claudia , Schneider Jürgen , Schoonvelde Martijn , Schulte-Cloos Julia , Schumann Sandy , Schunck Reinhard , Schupp Jürgen , Seuring Julian , Silber Henning , Sleegers Willem W. A. , 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 B. , Vagni Giacomo , Van Assche Jasper , van der Linden Meta , van der Noll Jolanda , Van Hootegem Arno , Vogtenhuber Stefan , Voicu Bogdan , Wagemans Fieke , Wehl Nadja , Wernere Hannah , Wiernik Brenton M. , Winter Fabian , Wolf Christof , Yamada Yuki , Zhang Nan , Ziller Conrad , Zins Stefan , Żółtak Tomasz , Nguyen Hung Hoang Viet 
Published: March 2021

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 include conscious and unconscious decisions that researchers make during data analysis and that may lead to diverging results. 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 research based on secondary data, we find that research teams reported widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers’ expertise, prior beliefs, and expectations barely predicted the wide variation in research outcomes. More than 90% of the total variance in numerical results remained unexplained even after accounting for research decisions identified via qualitative coding of each team’s workflow. This reveals a universe of uncertainty that is hidden when considering a single study in isolation. The idiosyncratic nature of how researchers’ results and conclusions varied is a new explanation for why many scientific hypotheses remain contested. It calls for greater humility and clarity in reporting scientific findings.