Coosje L. S. Veldkamp

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Statistical analysis is error prone. A best practice for researchers using statistics would therefore be to share data among co-authors, allowing double-checking of executed tasks just as co-pilots do in aviation. To document the extent to which this 'co-piloting' currently occurs in psychology, we surveyed the authors of 697 articles published in six top(More)
A survey in the United States revealed that an alarmingly large percentage of university psychologists admitted having used questionable research practices that can contaminate the research literature with false positive and biased findings. We conducted a replication of this study among Italian research psychologists to investigate whether these findings(More)
BACKGROUND Personality influences decision making and ethical considerations. Its influence on the occurrence of research misbehavior has never been studied. This study aims to determine the association between personality traits and self-reported questionable research practices and research misconduct. We hypothesized that narcissistic, Machiavellianistic(More)
We respond to the commentaries Waldman and Lilienfeld (Psychometrika, 2015) and Wigboldus and Dotch (Psychometrika, 2015) provided in response to Sijtsma's (Sijtsma in Psychometrika, 2015) discussion article on questionable research practices. Specifically, we discuss the fear of an increased dichotomy between substantive and statistical aspects of research(More)
The designing, collecting, analyzing, and reporting of psychological studies entail many choices that are often arbitrary. The opportunistic use of these so-called researcher degrees of freedom aimed at obtaining statistically significant results is problematic because it enhances the chances of false positive results and may inflate effect size estimates.(More)
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