Just out: a very peculiar paper for two reasons ..

Kaiser, T., Del Guidice, M., & Booth, T. (2019). Global sex differences in personality: Replication with an open online dataset. Journal of Personality (https://onlinelibrary.wiley.com/doi/epdf/10.1111/jopy.12500 ), In Press, , 1-15. [open-access]

Abstract

Objective: Sex  differences  in  personality  are  a  matter  of  continuing  debate.  In  a  study  on  the  United  States  standardization  sample  of  Cattell's  16PF  (fifth  edition),  Del Giudice and colleagues (2012; PLoS ONE, 7, e29265) estimated global sex differences in personality with multigroup covariance and mean structure analysis. The study found a surprisingly large multivariate effect, D = 2.71. Here we replicated the original analysis with an open online dataset employing an equivalent version of the 16PF.

Method: We closely replicated the original MG‐MCSA analysis on N = 21,567 U.S. participants (63% females, age 16–90); for robustness, we also analyzed N = 31,637 participants across English‐speaking countries (61% females, age 16–90).

Results: The size of global sex differences was D = 2.06 in the United States and D  =  2.10  across  English‐speaking  countries.  Parcel‐allocation  variability  analysis  showed that results were robust to changes in parceling (U.S.: median D = 2.09, IQR [1.89, 2.37]; English‐speaking countries: median D = 2.17, IQR [1.98, 2.47]).

Conclusions: Our results corroborate the original study (with a comparable if some-what smaller effect size) and provide new information on the impact of parcel allocation. We discuss the implications of these and similar findings for the psychology of sex differences

Why peculiar?

1. At no time do the authors actually indicate the magnitude of differences in the metric of the assessment being used. Instead, everything is reported as Cohen d effect sizes.

2. The vast majority of single-scale sex-difference Cohen ds are well below the minimum recommended practical effect size of 0.41 – from Table 1, Ferguson, C.J. (2009). An effect size primer: A guide for clinicians and researchers. Professional Psychology: Research and Practice, 40, 5, 532-538. The “big” D of 2.01 is a ‘multivariate’ effect .. whatever that means when we try and talk about a “global personality”. Indeed, the whole concept seems weird from a psychological perspective, making sense only in the context of multivariate statistical theory.

In short, this looks more like statistical make-work rather than something of any serious psychological substance. Without knowledge of actual magnitude differences, where those average magnitudes are located within each scale metric, and a justification of the meaningfulness of using a numerical representation system as isomorphic to variations in human personality attributes (i.e. are the numerical, additive-unit differences even noticeable by observers), all we have are statistical analyses devoid of any substantive psychological meaning.

And who is the ‘global personality’ a personality of exactly? After Laajaj, R., Macours, K., Hernandez, D.A.P., Arias, O., Gosling, S.D., Potter, J., Rubio-Codina, M., & Vakis, R. (2019). Challenges to capture the big five personality traits in non-WEIRD populations. Science Advances (https://advances.sciencemag.org/content/5/7/eaaw5226 ), 5,eaaw5226, 7, 1-13, how are psychologists to take this notion seriously anymore?

Regards .. Paul

Chief Research Scientist

Cognadev Ltd.

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