Thursday, 15 November 2012

False-Positive Psychology

Simmons JP, Nelson LD, Simonsohn U. (2011) False-positive psychology: undisclosed flexibility in data collection and analysis allows presenting anything as significant. Psychological Science. 2011 Nov;22(11):1359-66. Epub 2011 Oct 17.

This article addresses the elephant in the room of statistical analysis in the social sciences - how perfectly legitimate analysis decisions made by researchers can lead to ever increasing chances of making Type I errors (finding significance where none exists). Using basic modelling techniques, it was shown that simple analysis decisions can very quickly increase the chances of making a Type I error from 5% to over 60%. In a follow up paper (, the authors suggest a simple solution - adding, and acting on, 21  words to every methods section "We report how we determined our sample size, all data exclusions (if any), all manipulations, and all measures in the study." 

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