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  • Marjan Bakker
Degrees of Freedom in Planning, Running, Analyzing, and Reporting Psychological Studies: A Checklist to Avoid p-Hacking
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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. In this review article, we present an extensive list of 34 degrees of freedom that researchers have in formulating hypotheses, and in designing, running, analyzing, and reporting of psychological research. The list can be used in research methods education, and as a checklist to assess the quality of preregistrations and to determine the potential for bias due to (arbitrary) choices in unregistered studies.

Subject:
Psychology
Material Type:
Reading
Provider:
Frontiers in Psychology
Author:
Coosje L. S. Veldkamp
Hilde E. M. Augusteijn
Jelte M. Wicherts
Marcel A. L. M. van Assen
Marjan Bakker
Robbie C. M. van Aert
Date Added:
08/07/2020
Degrees of Freedom in Planning, Running, Analyzing, and Reporting Psychological Studies: A Checklist to Avoid p-Hacking
Unrestricted Use
CC BY
Rating

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. In this review article, we present an extensive list of 34 degrees of freedom that researchers have in formulating hypotheses, and in designing, running, analyzing, and reporting of psychological research. The list can be used in research methods education, and as a checklist to assess the quality of preregistrations and to determine the potential for bias due to (arbitrary) choices in unregistered studies.

Subject:
Psychology
Material Type:
Reading
Author:
Coosje L. S. Veldkamp
Hilde E. M. Augusteijn
Jelte M. Wicherts
Marcel A. L. M. van Assen
Marjan Bakker
Robbie C. M. van Aert
Date Added:
11/25/2016
Willingness to Share Research Data Is Related to the Strength of the Evidence and the Quality of Reporting of Statistical Results
Unrestricted Use
CC BY
Rating

Background The widespread reluctance to share published research data is often hypothesized to be due to the authors' fear that reanalysis may expose errors in their work or may produce conclusions that contradict their own. However, these hypotheses have not previously been studied systematically. Methods and Findings We related the reluctance to share research data for reanalysis to 1148 statistically significant results reported in 49 papers published in two major psychology journals. We found the reluctance to share data to be associated with weaker evidence (against the null hypothesis of no effect) and a higher prevalence of apparent errors in the reporting of statistical results. The unwillingness to share data was particularly clear when reporting errors had a bearing on statistical significance. Conclusions Our findings on the basis of psychological papers suggest that statistical results are particularly hard to verify when reanalysis is more likely to lead to contrasting conclusions. This highlights the importance of establishing mandatory data archiving policies.

Subject:
Psychology
Material Type:
Reading
Provider:
PLOS ONE
Author:
Dylan Molenaar
Jelte M. Wicherts
Marjan Bakker
Date Added:
08/07/2020