| Sir Roy George Douglas Allen | |
| Honorific Suffix: | CBE |
| Birth Date: | 1906 6, df=y |
| Birth Place: | Stoke-on-Trent, Staffordshire, England |
| Death Date: | [1] |
| Death Place: | Southwold, Suffolk, England |
| Field: | Statistics |
| Work Institutions: | London School of Economics |
| Alma Mater: | University of Cambridge |
| Known For: | Partial elasticity of substitution |
| Prizes: | Guy Medal (gold, 1978) |
Sir Roy George Douglas Allen, CBE, FBA (3 June 1906 – 29 September 1983) was an English economist, mathematician and statistician, also member of the International Statistical Institute.
Allen was born in Worcester and educated at the Royal Grammar School Worcester, from which he won a scholarship to Sidney Sussex College, Cambridge. He gained a First Class Honours in Mathematics, ranking top of his year as the Senior Wrangler.
He became a lecturer at the London School of Economics (LSE) later becoming Professor of Statistics. He wrote many papers and books on mathematical economics including the famous paper on A Reconsideration of the Theory of Value published in Economics in 1934 with Sir John Hicks.Other books include: Mathematical Analysis for Economists (1938), Statistics for Economists (1949), Mathematical Economics (1956), and Macroeconomic Theory (1967).
Allen was knighted in 1966 for his services to economics and became president of the Royal Statistical Society, who awarded him the Guy Medal in Gold in 1978. He was also treasurer of the British Academy of which he was a fellow (FBA).
He introduced the concept of "partial elasticity of substitution" to economics in his famous 1938 book Mathematical Analysis for Economists.
Allen became a fellow of Sidney Sussex, Cambridge and died in 1983. He had a son, Jeremy, who was a co-founder of the consultancy International Planning and Research, and a grandson, Dion.