**Ladislaus Josephovich Bortkiewicz** (August 7, 1868 – July 15, 1931) was Russian economist and statistician of Polish ancestry, who lived most of his professional life in Germany, where he taught at Strassburg University (Privatdozent, 1895–1897) and Berlin University (1901–1931).

Bortkiewicz was born in Saint Petersburg, Imperial Russia, where he graduated from the Law Faculty in 1890.

In 1898 he published a book about the Poisson distribution, titled *The Law of Small Numbers*. In this book he first noted that events with low frequency in a large population follow a Poisson distribution even when the probabilities of the events varied. It was that book that made the Prussian horse-kicking data famous. The data gave the number of soldiers killed by being kicked by a horse each year in each of 14 cavalry corps over a 20-year period. Bortkiewicz showed that those numbers followed a Poisson distribution. The book also examined data on child-suicides. Some have suggested that the Poisson distribution should have been named the "Bortkiewicz distribution."

In political economy, Bortkiewicz is important for his analysis of Karl Marx's reproduction schema in the last two volumes of *Capital*. Bortkiewicz identified a transformation problem in Marx's work. Making use of Dmitriev's analysis of Ricardo, Bortkiewicz proved that the data used by Marx was sufficient to calculate the general profit rate and relative prices. Though Marx's transformation procedure was not correct—because it did not calculate prices and profit rate simultaneously, but sequentially—Bortkiewicz has shown that it is possible to get the correct results using the Marxian framework, i.e. using the marxian variables constant capital and variable capital it is possible to obtain the profit rate and the relative prices in a three-sector model. This "correction of the Marxian system" has been the great contribution of Bortkiewicz to classical and Marxian economics but it was completely unnoticed until Paul Sweezy's 1942 book "Theory of Capitalist Development". Piero Sraffa (1960) has provided the complete generalization of the simultaneous method for classical and Marxian analysis.

Bortkiewicz died in Berlin, Germany. His papers, including a voluminous correspondence file (some 1,000 letters 1876–1931), were deposited at Uppsala University in Sweden, except for his correspondence with Léon Walras which went into the collection of the Walras scholar William Jaffe in the USA.

*Die mittlere Lebensdauer. Die Methoden ihrer Bestimmung und ihr Verhältnis zur Sterblichkeitsmessung*. Gustav Fischer, Jena 1893 (Göttinger Digitalisierungszentrum)
"Review of Léon Walras, *Éléments d'économie politique pure*, 2e édit.", 1890, *Revue d'économie politique*
Ladislaus Bortkiewicz (1898). *Das Gesetz der kleinen Zahlen* (PDF). Leipzig: B.G. Teubner.
Ladislaus von Bortkiewicz (1906). "Wertrechnung und Preisrechnung im Marxschen System: eine Übersicht über die Marx-Kritik" (PDF). *Archiv für Sozialwissenschaft*. **23**: 1–50. — Journal's 23rd Volume, 1906 (in German; Bortkiewicz' article starts on p.12 of the Pdf file) at archive.org — Article's English translation (*Value and Price in the Marxian System*), 1952, International Economic Papers, No.2
Ladislaus von Bortkiewicz (1949). "On the Correction of Marx's Fundamental Theoretical Construction in the Third Volume of *Capital*". In Paul M. Sweezy. *Karl Marx and the Close of his System*. New York: Augustus M. Kelley. pp. 197–221. — Spanish version 1917
Ladislaus Bortkiewicz (1917). *Die Iterationen — Ein Beitrag zur Wahrscheinlichkeitstheorie*. Berlin: Springer.
"Die Rodbertus'sche Grundrententheorie und die Marx'sche Lehre von der absoluten Grundrente", from: "Archiv für die Geschichte des Sozialismus und der Arbeiterbewegung", 1910–11