CAMBRIDGE, MA—A Harvard University study of more than 2,500 middle-income African-American families found that, when compared to other ethnic groups in the same income bracket, blacks were up to 23 percent more likely. "Our data would seem to discredit the notion that black Americans are less likely," said head researcher Russell Waterstone, noting the study also found that women of African descent were no more or less prone than Latinas. "In fact, over the past several decades, we've seen the African-American community nearly triple in probability." The study noted that, furthermore, Asian-Americans.