Though the study's conclusions gained a popular foothold and have been espoused by such noted figures as Bill Cosby, a later study obtained different results. In 2003, Karolyn Tyson, a sociologist, and William Darity Jr, an economist, both at the University of North Carolina at Chapel Hill, directed an 18-month study at eleven North Carolina schools which found that white and black students have essentially the same attitudes about scholastic achievement; students in both groups want to succeed in school and show higher levels of self-esteem when they do better in school. The results of this study have been published in a book by Stanford sociologist Prudence Carter