Sex and location as determinants of handedness: reply to Vuoksimaa and Kaprio (2010).
Martin M., Papadatou-Pastou M., Jones GV., Munafò MR.
In response to the comment by Vuoksimaa and Kaprio (2010) on our previous article on sex differences in left-handedness (Papadatou-Pastou, Martin, Munafò, and Jones, 2008), we carried out an additional meta-analysis to explore whether the widely observed tendency for rates of left-handedness to be greater among male than female individuals is also found in Scandinavian (Nordic) studies. The overall male-to-female ratio for left- to right-handedness odds provides evidence in favor of this hypothesis. However, the results were subject to a significant moderating effect related to nation of origin. We discuss the potential impact on observed measures of additive rather than multiplicative processes that may underlie sex differences in handedness and also the date-of-study effect on handedness rates.