Using both qualitative and quantitative analysis, Dr. Laird has compiled a unique catalog of data on every member of the Politburo since 1917. Central to the analysis is a "change index" that provides a running measure of politically motivated changes in Politburo membership. Examining continuities and changes in the Politburo over the years, the author shows that within each of the major leadership eras there were important subperiods marking significant policy changes. He also uses the index, along with other empirical measures, to explain successes and failures of specific policy...