The Lexis diagram, a misnomer

Abstract

Around 1870, demographers felt the need for a simple chart to present population dynamics. This chart is known as the Lexis diagram, but it is a misnomer. To be useful, this chart must allow for the systematic location on one plane of the three classical demographic co-ordinates, namely: the date, the age and the moment of birth. There are three solutions for this problem. In 1869, Zeuner worked out a first solution. In 1870, Brasche proposed a second one with networks of parallels; it is the version most currently used now. In 1874, Becker proposed the third one. In 1875, certainly after Verwey, Lexis took back the Zeunerís diagram and just added networks of parallels. In spite of all this, the name "Lexis diagram" has imposed itself in a seemingly invincible way.