The Life of <i>p</i>: “Just Significant” Results are on the Rise

Leggett, Nathan; Thomas, Nicole A.; Loetscher, Tobias; Nicholls, Michael E. R.

doi:10.1080/17470218.2013.863371

Cited by 67 publications

(101 citation statements)

References 19 publications

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“…Bakker and Wicherts (2011) found that 50% of the articles reporting the results of NHST tests in the psychological literature contained at least one such inconsistent p-value, and that 18% of the statistical results was incorrectly reported. Similar yet slightly lower error rates have been found in the medical literature (Berle & Starcevic, 2007;Garcia-Berthou & Alcaraz, 2004) and in recent replications (Bakker & Wicherts, 2014a;Caperos & Pardo, 2013;Leggett, Thomas, Loetscher, & Nicholls, 2013). Bakker and Wicherts (2011) discuss different reasons why these inconsistent p-values may appear.…”

Section: Statistical Reporting Errors and Collaboration On Statisticasupporting

confidence: 71%

“…We estimated the prevalence of inconsistent p-values in six top psychology journals by means of an automated procedure to retrieve and check errors in the reporting of statistical results, in order to replicate earlier estimates of error rates in the psychological literature Bakker & Wicherts, 2014a;Caperos & Pardo, 2013;Leggett et al, 2013). Our results show a somewhat higher probability for articles to contain at least one p-value that comprises an error compared to the two studies by Bakker and Wicherts (63% vs. 45% (2014a) and 50% (2011)), and a higher probability for articles to contain at least one p-value that comprises a gross error (20% vs. 15% (2011; 2014a)).…”

Section: Discussionmentioning

confidence: 99%

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Doctoral thesis: The human fallibility of scientists - dealing with error and bias in academic research

Veldkamp¹

2017

Preprint

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THE HUMAN FALLIBILITY OF SCIENTISTSDealing with error and bias in academic researchRecent studies have highlighted that not all published findings in the scientific literature are trustworthy, suggesting that currently implemented control mechanisms such as high standards for the reporting of research methods and results, peer review, and replication, are not sufficient. In psychology in particular, solutions are sought to deal with poor reproducibility and replicability of research results. In this dissertation project I considered these problems from the perspective that the scien¬tific enterprise must better recognize the human fallibility of scientists, and I examined potential solutions aimed at dealing with human error and bias in psychological science. First, I studied whether the human fallibility of scientists is actually recognized (Chapter 2). I examined the degree to which scientists and lay people believe in the storybook image of the scientist: the image that scientists are more objective, rational, open-minded, intelligent, honest and communal than other human beings. The results suggested that belief in this storybook image is strong, particularly among scientists themselves. In addition, I found indications that scientists believe that scientists like themselves fit the storybook image better than other scientists. I consider scientist’s lack of acknowledgement of their own fallibility problematic, because I believe that critical self-reflection is the first line of defense against potential human error aggravated by confirmation bias, hindsight bias, motivated reasoning, and other human cognitive biases that could affect any professional in their work. Then I zoomed in on psychological science and focused on human error in the use of null the most widely used statistical framework in psychology: hypothesis significance testing (NHST). In Chapters 3 and 4, I examined the prevalence of errors in the reporting of statistical results in published articles, and evaluated a potential best practice to reduce such errors: the so called ‘co-pilot model of statistical analysis’. This model entails a simple code of conduct prescribing that statistical analyses are always conducted independently by at least two persons (typically co-authors). Using statcheck, a software package that is able to quickly retrieve and check statistical results in large sets of published articles, I replicated the alarmingly high error rates found in earlier studies. Although I did not find support for the effectiveness of the co-pilot model in reducing these errors, I proposed several ways to deal with human error in (psychological) research and suggested how the effectiveness of the proposed practices might be studied in future research. Finally, I turned to the risk of bias in psychological science. Psychological data can often be analyzed in many different ways. The often arbitrary choices that researchers face in analyzing their data are called researcher degrees of freedom. Researchers might be tempted to use these researcher degrees of freedom in an opportunistic manner in their pursuit of statistical significance (often called p-hacking). This is problematic because it renders research results unreliable. In Chapter 5 I presented a list of researcher degrees of freedom in psychological studies, focusing on the use of NHST. This list can be used to assess the potential for bias in psychological studies, it can be used in research methods education, and it can be used to examine the effectiveness of a potential solution to restrict oppor¬tunistic use of RDFs: study pre-registration. Pre-registration requires researchers to stipulate in advance the research hypothesis, data collection plan, data analyses, and what will be reported in the paper. Different forms of pre-registration are currently emerging in psychology, mainly varying in terms of the level of detail with respect to the research plan they require researchers to provide. In Chapter 6, I assessed the extent to which current pre-registrations restricted opportunistic use of the researcher degrees of freedom on the list presented in Chapter 5. We found that most pre-registrations were not sufficiently restrictive, but that those that were written following better guidelines and requirements restricted opportunistic use of researcher degrees of freedom considerably better than basic pre-registrations that were written following a limited set of guidelines and requirements. We concluded that better instructions, specific questions, and stricter requirements are necessary in order for pre-registrations to do what they are supposed to do: to protect researchers from their own biases.

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Section: Statistical Reporting Errors and Collaboration On Statisticasupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Doctoral thesis: The human fallibility of scientists - dealing with error and bias in academic research

Veldkamp¹

2017

Preprint

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“…This suggests that a psychologist's admission to a QRP that is less often admitted to by others usually implies his or her admission to QRPs with a higher admission rate in the entire sample. Given that rounding down p-values close to .05 was one of the QRPs with relatively low admission rates, the frequency of misreported p- Previous research found a decrease in negative results (Fanelli, 2012) and an increase in reporting inconsistencies (Leggett, Thomas, Loetscher, & Nicholls, 2013) suggesting that QRPs are on the rise. On the other hand, it has been found that the number of published corrections to the literature did not change over time, suggesting no change in QRPs over time (Fanelli, 2013(Fanelli, , 2014.…”

Section: Most Conclusion In Psychology Are Based On the Results Of Nmentioning

confidence: 99%

“…Leggett et al (2013) recently studied reporting errors in two main psychology journals in 1965 and 2005. They found that the increase in reporting inconsistencies over the years was higher in the Journal of Personality and Social Psychology (JPSP), the flagship journal of social psychology, than in Journal of…”

Section: Most Conclusion In Psychology Are Based On the Results Of Nmentioning

confidence: 99%

Research on Research: A Meta-Scientific Study of Problems and Solutions in Psychological Science

Nuijten¹

2018

Preprint

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SUMMARY DOCTORAL DISSERTATION: Psychology is facing a “replication crisis”. Many psychological findings could not be replicated in novel samples, which lead to the growing concern that many published findings are overly optimistic or even false. In this dissertation, we investigated potential indicators of problems in the published psychological literature. In Part I of this dissertation, we looked at inconsistencies in reported statistical results in published psychology papers. To facilitate our research, we developed the free tool statcheck; a “spellchecker” for statistics. In Part II, we investigated bias in published effect sizes. We showed that in the presence of publication bias, the overestimation of effects can become worse if you combine studies. Indeed, in meta-analyses from the social sciences we found strong evidence that published effects are overestimated. These are worrying findings, and it is important to think about concrete solutions to improve the quality of psychological research. Some of the solutions we propose are preregistration, replication, and transparency. We argue that to select the best strategies to improve psychological science, we need research on research: meta-research.

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“…"(Aitkenhead, 2013) P-hacking is the practise of getting the results required regardless of the data by means of academic misconduct and rigged statistical testing. The mildest forms of p-hacking, from the author's personal experiences and others', are extremely widespread (Head et al, 2015;Lakens, 2015;Leggett et al, 2013;Masicampo and Lalande, 2012). This brings us to the crux of the present problems.…”

Section: Science Hackingmentioning

confidence: 96%

Crisis in What Exactly?

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The Life of p: “Just Significant” Results are on the Rise

Cited by 67 publications

References 19 publications

Doctoral thesis: The human fallibility of scientists - dealing with error and bias in academic research

Doctoral thesis: The human fallibility of scientists - dealing with error and bias in academic research

Research on Research: A Meta-Scientific Study of Problems and Solutions in Psychological Science

Crisis in What Exactly?

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