Étienne Laspeyres

Ernst Louis Étienne Laspeyres (; 28 November 1834 – 4 August 1913) was a German economist. He was Professor ordinarius of economics and statistics or State Sciences and cameralistics (public finance and administration) in Basel, Riga, Dorpat (now Tartu), Karlsruhe, and finally for 26 years in Gießen. Laspeyres was the scion of a Huguenot family of originally Gascon descent which had settled in Berlin in the 17th century, and he emphasised the Occitan pronunciation of his name as a link to his Gascon origins.

Work Laspeyres is mainly known today for his 1871 development of the index number formula method for determining price increases, used for calculating the rate of inflation. A type of this calculation is known today as the Laspeyres Index. In addition to his accomplishments in price indices, Laspeyres may be counted as one of the fathers of business administration as an academic-professional discipline in Germany, and as one of the main unifiers of economics and statistics by "developing ideas which are today by and large nationally and internationally reality: quantification and operationalization of economics; expansion of official statistics; cooperation of official statistics and economic research; and integration of the economist and the statistician in one person." (Rinne 1983) In economics, Laspeyres was to some extent a representative of the Historical School and certainly of Kathedersozialismus.

The surname Laspeyres is of Gascon origin; his ancestors were Huguenots who settled in Berlin in the 17th century. How he pronounced his surname is uncertain, but likely as "Las-pay-ress".