The Problem With Michael LaCour's Rebuttal

The hottest story in science over the past couple of weeks has been the accusations of fraud against UCLA political science PhD student Michael LaCour. The allegations were posted online on May 19th and they concern one of LaCour's papers, published in Science, called When contact changes minds: An experiment on transmission of support for gay equality. On May 28th the paper was retracted on the request of LaCour's co-author, Donald Green, but LaCour stands by the data and disagreed with the retraction. There have been lots of twists and turns in this case - LaCour has admitted lying about some aspects of the data collection. In this post however I'll focus on the data and on LaCour's rebuttal to the original accusations, which he posted on May 29th. LaCour's key data are measures of attitudes towards gay marriage, using a 0-100 scale called a 'feeling thermometer.' LaCour measured this at baseline and then at subsequent timepoints. According to the accusers, led by David Broockman, LaCour's baseline feeling thermometer data are statistically indistinguishable from an large existing gay marriage feeling thermometer dataset called CCAP. The implication is that LaCour faked his data by randomly selecting datapoints from CCAP. The critics showed histograms of the two baseline datasets in LaCour and Green (2014) and of the CCAP thermometer. It can be seen that they're virtually identical and a statistical test confirms this at p = 0.4776, no significant difference.