On March 26, 1821, German statistician Ernst Engel was born. Engel was head of the Prussian Statistical Bureau (1860-82) and is best known for the “Engel curve,” or Engel‘s law, which states that the proportion of expenditure on food will fall as income rises, i.e. food is a necessary good.
Ernst Engel studied at the Freiberg University of Mining and Technology, in Saxony, and on completing his curriculum traveled in Germany and France. After the German revolutions of 1848 and 1849, Engel was attached to the royal commission in Saxony appointed to determine the relations between trade and labor.
One year later, Engel was directed by the government to assist in the organization of the German Industrial Exhibition of Leipzig. He earned a good reputation and in 1854, he entered the government service as chief of the newly instituted statistical department. There, Engel earned himself a worldwide reputation and later raised to the rank of ‘Geheimer Regierungsrat’.
Ernst Engel became most famous for Engel’s law. It describes an observation in economics and states that as income rises, the proportion of income spent on food falls, even if the actual expenditure on food rises. This further means that income elasticity of demand of food is between 0 and 1. One application of this statistic is treating it as a reflection of the living standard of a country. As this proportion or ‘Engel coefficient‘ increases, the country is by nature poorer, conversely a low Engel coefficient indicates a higher standard of living. It has the advantage over the commonly used prosperity indicator of gross domestic product that the local price level is automatically taken into account. Engel’s law is one of the best-proven empirical laws of economics.
In microeconomics, an Engel curve describes how household expenditure on a particular good or service varies with household income. There are two varieties of Engel curves. Budget share Engel curves describe how the proportion of household income spent on a good varies with income. Alternatively, Engel curves can also describe how real expenditure varies with household income. In microeconomics Engel curves are used for equivalence scale calculations and related welfare comparisons, and determine properties of demand systems such as aggregability and rank. Engel curves have also been used to study how the changing industrial composition of growing economies are linked to the changes in the composition of household demand. In trade theory, one explanation of inter-industry trade has been the hypothesis that countries with similar income levels possess similar preferences for goods and services (the Lindner hypothesis), which suggests that understanding how the composition of household demand changes with income may play an important role in determining global trade patterns.
From 1882 he retired to the Villa Engel in Serkowitz, now part of Radebeul, but continued his research. He was also Chairman of the Supervisory Board of the Neubrunn Waterworks and of the Lößnitz Embellishment Association. Engel died 1896 in Serkowitz at age 75.
References and Further Reading:
-  Short Biography of Ernst Engel
-  Ernst Engel at Deutsche Biografie in German
-  Engel’s Law
-  Ernst Engel at Wikidata
-  “Engel, Ernst.” International Encyclopedia of the Social Sciences. . Encyclopedia.com.