The case of Diederik Stapel

Allegations of scientific fraud by prominent Dutch social psychologist are investigated by multiple universities.

By Mieke Verfaellie and Jenna McGwin

In recent months, the scientific fraud allegations surrounding prominent Dutch social psychologist Diederik Stapel have intensified. Inquiry committees convened at Tilburg University, the University of Groningen, and the University of Amsterdam indicate that the research misconduct committed by Stapel was vast. The misconduct goes back to at least 2004 and involves the manipulation of data and complete fabrication of entire experiments. The fraudulent data are said to have been used in at least 30 published, peer-reviewed papers.

An interim report (PDF, 385KB) published by Tilburg University on October 31, 2011, incorporating findings from the inquiry committees in Groningen and Amsterdam, examines the scope of the misconduct and explores the academic culture that allowed Stapel to continue his fraudulent research behaviors for such an extended period of time. The report indicates that the individuals most directly affected were masters and doctoral students working with Stapel, and unfortunately, a number of dissertations are thought to be based on fabricated data. In addition, colleagues of Stapel have also unknowingly used fabricated data. In these instances, Stapel would contact a colleague and indicate that he had a not-yet-analyzed dataset that fit perfectly with a research question the colleague was examining. Stapel would ask if the colleague was interested in analyzing and writing up the results, and in turn, he would be listed as co-author on the publication. In either situation, there has been no evidence to suggest that students or other co-authors were aware of any misconduct.

The interim report states that three junior researchers in the psychology department became suspicious when they discovered irregularities in several of Stapel’s published papers and brought the information to the head of the department. The report also states that several other junior researchers and faculty members raised concern previously, but these reports were not acted upon.

In a recent Nature article, social psychologist Jennifer Crocker, who serves as chair of the American Psychological Association’s Publications and Communications Board, states that “to understand fraud, we should think about how it begins and escalates, not how it ends. By the time such fraud is exposed, bad choices that would usually lead to only minor transgressions have escalated into outright career-killing behavior.” Thus, the question arises: what type of academic culture allowed Stapel to continue his misconduct for so long? The interim report points to two factors that contributed to the misconduct going unnoticed for such an extended period of time:

1.  The sophisticated way in which Stapel used his power and prestige. Stapel was known as a charismatic leader with great dedication to his students and colleagues. There was often a phase of intensive preparation of the research with the student. After developing experimental materials, the data collection was completely in the hands of Stapel. The so-called data collection occurred at secondary schools where Stapel had connections, and occurred under his sole supervision. He enlisted the help of unknown (fictitious) paid research assistants for data collection. After a few weeks, a complete, coded data set would be made available to the collaborator for further analysis. The collaborator could then immediately focus on manuscript writing. Stapel justified doing the research at secondary schools because students there were more naïve and therefore “better research participants.” He did not allow collaborators to approach the schools, as schools might be overwhelmed with research requests and this would jeopardize his access. Stapel was described as intimidating and not tolerating questions from students regarding his refusal to have them involved in data collection. There was some discussion among students and junior researchers about his complete control over the data, but in the end it was felt that he was doing them a service.

2.  Poor functioning of scientific scrutiny and criticism. A number of “red flags” should have been raised, including:

  • Colleagues were not aware of the fact that doctoral students did not collect their own data;

  • When students asked to see completed questionnaires, they were told that neither the schools nor Stapel had room to store them;

  • Insufficient clarity in the manuscripts as to how data were collected;

  • Data too good to be true (e.g., large effect sizes, small standard deviations);

  • Strange or improbable data patterns (e.g., cutting and pasting of identical scores in difference columns);

  • The culture in social psychology where data is not made publicly available; and

  • Failure on the part of the university to have an ombudsman in the department to whom whistleblowers could go. Any concern regarding scientific integrity was to be reported directly to the Rector, which contrasts with other universities in the Netherlands.

The conclusion of the report states several recommendations: 

  • Doctoral students at Tilburg University should have two supervisors; 

  • Dissertation committees at Tilburg University must ascertain that the student collected the data; 

  • There should be a “research integrity” moderator within the department to whom whistleblowers can go; 

  • Research data need to remain available for five years; and 

  • Manuscripts need to indicate where the data reside and how they can be accessed.

Although this case reflect poorly on the field of psychology, it is important to note that research misconduct occurs in all scientific disciplines. The recommendations arising from the investigation of the Stapel case are worth considering by scientists and departments in all fields.

According to Inside Higher Ed, Stapel has voluntarily returned his doctorate to the University of Amsterdam, stating in a letter that his conduct “does not fit with the duties associated with a doctorate.”


Crocker, J. (2011). The road to fraud starts with a single step. Nature, 479, 151.

Jump, P. (2011, November 28). A star’s collapse. Inside Higher Ed.

Tilburg University (2011). Interim report regarding the breach of scientific integrity committed by prof. D.A. Stapel. (PDF, 385KB) Tilburg University, 1-21.

Mieke Verfaellie, PhD (VA Boston Healthcare System and Boston University School of Medicine) is a member of the American Psychological Association’s Committee for Human Research. Jenna McGwin, MS, is Research Ethics Program Associate in the APA Research Ethics Office.