Fernando Cartwright’s research while affiliated with University of Alberta and other places

... Two groups of participants in the lower and upper quartiles of MA scores were identified. Individuals from the upper quartile mainly consisted of women (60 women and 5 men), primarily because a larger number of women were screened and because, in line with the literature, there are higher prevalence rates of MA symptoms among females than males (e.g., Baloğlu & Koçak, 2006;Else-Quest et al., 2010;Ma & Cartwright, 2003). Given that MA is moderately related to general anxiety and gender (Devine et al., 2012;Hembree, 1990), the two groups were matched in terms of general anxiety and gender to reduce the bias arising from these confounding variables. ...

Reference:

Emotional processing of math-related words in people with math anxiety