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Measuring the Unmeasurable
- S. Gruijters, Bram P. I. Fleuren
- Psychology, BiologyHuman Nature
- 15 November 2017
It is argued that current psychometric approaches attempting to identify K-factors are based on an unwarranted conflation of functional descriptions and proximate mechanisms and that life history strategy cannot be identified with psychometrics as usual.
Sex, germs, and health: pathogen-avoidance motives and health-protective behaviour
- S. Gruijters, J. Tybur, R. Ruiter, K. Massar
- Psychology, MedicinePsychology & health
- 6 April 2016
It is argued that understanding and targeting pathogen-avoidance psychology can add novel and important understanding of health-protective behaviour.
The reasoned actions of an espresso machine: a comment on Peters and Crutzen (2017)
- S. Gruijters
- PsychologyHealth psychology review
- 3 April 2017
In ‘Pragmatic nihilism: How a theory of nothing can help health psychology progress’, Peters and Crutzen (2017) discuss a question relevant to many in psychology: What are we actually measuring? Ac...
Using principal component analysis to validate psychological scales: Bad statistical habits we should have broken yesterday II
- S. Gruijters
- Psychology
- 1 May 2019
In this short paper, I review some reasons why the use of PCA finds little justication in the context of validating psychological scales. I make a case for the burgeoning use of better alternatives…
Baseline comparisons and covariate fishing: Bad statistical habits we should have broken yesterday
- S. Gruijters
- Psychology
- 8 November 2016
Checks on baseline differences in randomized controlled trials (RCTs) are often done using nullhypothesis significance tests (NHSTs). In a quick scan of recent publications in the journal Psychology…
Meaningful change definitions: sample size planning for experimental intervention research
- S. Gruijters, G. Peters
- BusinessPsychology & health
- 8 August 2019
The proposed method requires setting a meaningful change definition and is specifically suited for applied researchers interested in planning tests of intervention effectiveness, and provides a hands-on walk through of the method and easy-to-use R functions to implement it.
Making inferential leaps: Manipulation checks and the road towards strong inference
- S. Gruijters
- PsychologyJournal of Experimental Social Psychology
- 20 August 2020
This paper posits that manipulation checks do not improve the authors' inferences to causal explanations, but instead result in weaker hypothesis tests, and advocates four methodological heuristics, offered as alternatives to manipulation validity checks, to more severely test causal hypotheses.
Introducing the Numbers Needed for Change: A practical measure of effect size for intervention research
- S. Gruijters, G. Peters
- Psychology
- 31 March 2017
Pregnant Women’s View on Their Relationship: A Comparison With Nonpregnant Women
- K. Massar, A. Buunk, S. Gruijters
- Psychology
- 20 December 2013
The positive effects of partner support on pregnancy outcomes and maternal (mental) health are well established in the literature. Less is known about pregnant women’s perceptions of their partner…
Introducing the Numbers Needed for Change (NNC): an effect size that connects research to practice
- S. Gruijters, G. Peters
- Psychology
- 31 December 2017
Effect size indices are valuable to research in health psychology, but generic measures (e.g. Cohen’s d or point-biserial correlation) are limited in their ability to convey practical information…
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