Diederik Alexander Stapel (born 19 October 1966) is a Dutch former professor of social psychology at Tilburg University. In 2011 Tilburg University suspended Stapel for fabricating and manipulating data for his research publications. This scientific misconduct took place over a number of years and affected dozens of his publications. By 2015, fifty-eight of Stapel's publications had been retracted. He has been described in coverage by the New York Times as "the biggest con man in academic science".
Early life
Stapel was born in the village of Oegstgeest, near Leiden, the youngest of four children. His father worked as a civil engineer.
After completing his schooling, Stapel studied drama and media studies at East Stroudsburg University in Pennsylvania before moving back to the Netherlands for an undergraduate degree in psychology. Stapel obtained an M.A. in psychology and communication science in 1991 from the University of Amsterdam(). From the same university he obtained his PhD cum laude in social psychology in 1997; his dissertation was on assimilation and contrast effects. Before embarking on his PhD, in 1991–1992, Stapel returned to the US for study, undertaking a program on behavioral decision making at the University of Chicago's Graduate School of Business.
He married in 1997; Stapel and his wife had first met in high school.
Career
After gaining his PhD, Stapel continued at UvA as a fellow of the Royal Netherlands Academy of Arts and Sciences () for three years. Stapel became a professor at the University of Groningen in 2000 and moved to Tilburg University in 2006, where he cofounded TiBER, the Tilburg Institute for Behavioral Economics Research. In September 2010, Stapel became dean of the social and behavioral sciences faculty.
Stapel received the Career Trajectory Award from the Society of Experimental Social Psychology in 2009, which has since been retracted. He voluntarily surrendered his PhD title to the University of Amsterdam in November 2011, noting that his "behavior of the past years are inconsistent with the duties associated with the doctorate". This action was taken into account in the decision of Dutch prosecutors to not pursue criminal actions.
Scientific misconduct
Investigations
In September 2011, Tilburg University suspended Stapel due to his fabrication of data used in research publications. The university announced an investigation of his work.
On 31 October 2011, a committee entrusted with investigating "the extent and nature of the breach of scientific integrity committed by Mr D.A. Stapel", formed by the Rector Magnificus of Tilburg University and chaired by Willem ("Pim") Levelt, published an interim report regarding Stapel's activities at the three Dutch universities where he had worked.
Stapel provided the investigating committees with a list of his publications that contained fictitious data, acknowledging that it may not be complete.
An extensive report analyzes all 130of Stapel's articles and twenty-four book chapters. A website was set up on 27 March 2012 to publish interim findings. According to the first findings, out of an initial batch of twenty Stapel publications studied by the Levelt committee, twelve journal articles were fabricated and three contributions to books were also fraudulent. The Netherlands newspaper de Volkskrant reported that the final report was due on 28 November 2012, and that a book by Stapel was to be released around the same time.
"We have some 30papers in peer-reviewed journals where we are actually sure that they are fake, and there are more to come," Pim Levelt, chair of the committee investigating Stapel's work said in a media statement.
Suspicions raised
The Levelt joint committees' reports acknowledged three unnamed young Tilburg University researchers as the whistleblowers for the case. The whistleblowers had become suspicious when one noticed anomalous data they had received from Stapel. Subsequent discussion with Stapel did not allay their concerns. The three spent several months conducting their own enquiries using data files Stapel had supplied. Once they felt they had sufficient evidence, they approached the head of the Department of Social Psychology, Marcel Zeelenberg. The students' evidence was convincing enough that Zeelenburg brought it directly to the , Philip Eijlander. Official investigations were set in motion within days by Tilburg University, which were soon joined by the UvA and the University of Groningen.
The Levelt report also noted two professors who claim they had previously seen examples of Stapel's data that were "too good to be true."