Varieties of Voodoo
Ed Vul
Department of Brain and Cognitive Sciences
Massachusetts Institute of Technology

fMRI experiments provide an abundance of data, of which only a small, a priori unknown, subset is relevant. As such, experimenters are faced with a challenging statistical problem: How to estimate both the location of the signal as well as the strength of the signal? (e.g., Which bit of the brain is correlated with neuroticism, and what is the strength of the correlation?) I will argue that current analysis techniques lead to overestimates of signal strength (e.g., correlation magnitude), that have gone largely unnoticed by researchers. I will advocate several simple analysis strategies that avoid this overestimation, produce unbiased estimates of signal (correlation or otherwise), and afford quantitative population-level inferences.


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