Lexis graduated in 1859 from U Bonn, where he had studied mathematics and physics. His subsequent career focused on the social sciences: at various times he held chairs in economics, geography, and political science. In 1879 he published On the Theory of the Stability of Statistical Series which began the study of time series. Lexis was a pioneer of the analysis of demographic time series.

http://static.twoday.net/gregorbrand/images/Lexis.jpg Photograph.