more than one job at a time, and has been shown to have deteriorating effects on women's health. Causes Gender ideology "Gender ideologies are linked to beliefs about appropriate behaviour for men and women". Socialization plays a major role in determining gender ideologies and what's valued in one time and culture may not necessarily transcend to another. Traditional gender ideologies have contributed to the double burden because it posits women as caretakers, men as providers, and each gender occupying their own sphere of influence. Although research has shown that attitudes about gender roles have become more egalitarian over the past few decades, "these changes in gender attitudes have not been accompanied by corresponding changes in the allocation of housework". Labor market constraints Despite women's increasing participation in the work force, a gender division of labor persists. There are a number of constraints in the labor market that contribute to the double burden. "Women are disproportionately represented in informal work and concentrated among lower-quality jobs within self-employment." The informal market is generally precarious and characterized by low wages, few benefits, and a lack of social protections that are offered in the formal market. Even within the formal market, there is occupational segregation and a gender wage gap. Occupational segregation can be either horizontal or vertical: horizontal segregation limits women to certain sectors and occupations, while vertical segregation restricts them to particular positions within occupational hierarchies. Men and women are even found at different levels of the occupational hierarchy. The "glass ceiling" is the relative absence of women in senior or managerial positions due to institutional barriers and norms. Even in female-dominated occupations, men often occupy the more skilled and better paid positions. The gender wage gap is a possible consequence of occupational segregation. The gender wage gap is the "difference between wages earned by women and men". In 2008, globally, men were estimated to earn 16.5 per cent more than women. The gender wage gap is narrowing, but progress remains slow. Additionally, the narrowing of the gender wage gap may be attributed to a decrease in men's wages instead of an increase in women's wages. "The persistent gender wage gap across regions may reflect a number of factors, including women's continued disadvantage in terms of education and skills; their lack of an organized voice and bargaining power; gender-specific constraints on their labour market mobility; and their relatively high involvement in part-time