(Mis-)understanding COVID-19 and digit ratio: Methodological and statistical issues in Manning and Fink (2020)

Abstract

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Sex differences in the relationship between digit ratio (2D:4D) and national case fatality rates for COVID-19: A reply to Sahin (2020)

“…It also replicates the null finding of Jones et al [4] for an association between 2D:4D and the percent male deaths in a smaller and less reliable sample. Jones et al's [4] focus on this without considering the main finding of 2D:4D and national CFR's for COVID-19 had the effect of obfuscating the latter [3].…”

“…Thus, the re-analysis extends previous findings of sex differences in mortality (males > females) in the relationship between 2D:4D and national CFR's for COVID-19 [2]. It also replicates the null finding of Jones et al [4] for an association between 2D:4D and the percent male deaths in a smaller and less reliable sample. Jones et al's [4] focus on this without considering the main finding of 2D:4D and national CFR's for COVID-19 had the effect of obfuscating the latter [3].…”

A further analysis of Manning and Fink (2020)

“…Manning and Fink also find a positive association between 2D:4D and the percentage of male death from COVID-19. However these results, especially association between 2D:4D and percentage of male death from COVID-19, are challenged by Jones et.al [2].…”

“…Estimation results of this model is given Table 2, which show that both variables are in each case are significantly different from zero, albeit with different signs. As an additional analysis we also used data provided by Jones et.al [2] to estimate male death rates as a function of the independent variables. We find that same quantitative results hold, which is given in Table 3.…”

No credible evidence for links between 2D:4D and COVID-19 outcomes: A probabilistic perspective on digit ratio, ACE variants, and national case fatalities

“…In addition, the association between human androgen receptor genes and 2D:4D are almost exactly null (16), as well as the association between circulating testosterone and continuous 2D:4D measures (17,18), and changes in testosterone and physical exercise (19), all of which suggests the basic biological mechanisms underpinning 2D:4D as a measure of any kind of testosterone exposure are weak to non-existent. In response to a similar criticism by Jones et al, (20) Manning and Fink (2) point out that 2D:4D shows associations with prenatal androgen exposure in discussions of sexual orientation (21) and gender dysphoria (22), but the direct evidence that higher levels of prenatal androgen impact later outcomes is missing. However, others demonstrate that 2D:4D is associated with amniotic fluid testosterone, but only in limited cases, such as for the left hands of females only (23), which makes its association with more severe COVID-19 for males difficult to reconcile.…”