Kazuo Yamaguchi is the Ralph Lewis Professor. He was department chair in 2008-2011, and was Hanna Holborn Gray Professor in 2005-2013. Yamaguchi is interested in statistical models for social data and mathematical models for social phenomena, life course, rational choice theory, stratification and mobility, demography of family and employment, process of drug use progression, and Japanese society. His current research focuses on methodology (causal models for categorical data, decomposition analysis, and panel data analysis), and gender inequality and work-life balance in Japan and Korea.