Irregularities in LaCour (2014)

David Broockman, Assistant Professor, Stanford 

Joshua Kalla, Graduate Student, UC Berkeley

Peter Aronow, Assistant Professor, Yale University,

May 19, 2015

Summary:  We report a number of irregularities in the replication dataset posted for LaCour and Green (Science “When contact changes minds: An experiment on transmission of support for gay equality,” 2014) that jointly suggest the dataset (LaCour 2014) was not collected as described. These irregularities include baseline outcome data that is statistically indistinguishable from a national survey and over-time changes that are unusually small and indistinguishable from perfectly normally distributed noise. Other elements of the dataset are inconsistent with patterns typical in randomized experiments and survey responses and/or inconsistent with the claimed design of the study.

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