The apparent narrowing of the wage gap between working men and women in the last 30 years reflects changes in the type of women in the workforce, rather than in how much they're being paid, according to groundbreaking new research by Brown University economist Yona Rubinstein and Casey Mulligan of the University of Chicago. Rubinstein says the impression that the labor market treats women better today than three decades ago is a "statistical illusion." The findings are published in the August issue of The Quarterly Journal of Economics.