Sir Ronald Aylmer Fisher FRS (17 February 1890 – 29 July 1962) was a British statistician, evolutionary biologist, geneticist, and eugenicist. He is widely regarded as one of the most important figures in 20th-century statistics and a principal architect of the modern evolutionary synthesis. Fisher's groundbreaking work laid the foundations for much of modern statistical theory and practice, including the analysis of variance (ANOVA), principles of experimental design, maximum likelihood estimation, and fiducial inference. While not an economist by profession, his statistical methodologies have had a profound and transformative impact on econometrics and quantitative economic research.

1. Early Life and Education
2. Career and Major Scientific Contributions
2.1. Statistics
2.2. Evolutionary Biology and Genetics
3. Impact on Economics and Econometrics
   3.1. Application of Statistical Methods
   3.2. Experimental Design in Economic Research
   3.3. Foundations for Econometric Modeling
4. Eugenics
5. Honours and Later Life
6. Influence and Legacy
7. List of Major Works (with relevance to statistical methods used in economics noted)
8. See Also

Ronald Aylmer Fisher was born in East Finchley, London, England, to George Fisher, a partner in a fine arts auctioneering firm, and Kate Heath. He had a twin brother who died in infancy. Fisher demonstrated exceptional mathematical aptitude from a very young age but suffered from extremely poor eyesight, which often required him to learn mathematics without the aid of visual representation, developing his remarkable ability for geometrical intuition.

He attended Harrow School on a scholarship and then won a scholarship to Gonville and Caius College, Cambridge, where he studied mathematics, graduating as a Wrangler in the Mathematical Tripos in 1912. He also developed a keen interest in biology during his time at Cambridge.

Fisher's career spanned several institutions and fields, but his work was unified by a powerful combination of mathematical insight and practical application.

Fisher is often called "the single most important figure in 20th century statistics." His contributions revolutionized the field.

• Rothamsted Experimental Station (1919–1933): Much of his foundational statistical work was done while he was employed as a statistician at Rothamsted, an agricultural research station. He was tasked with analyzing vast amounts of data from crop experiments conducted over many decades. This practical need spurred many of his theoretical innovations.

Fisher developed ANOVA as a method for partitioning the observed variance in a dataset into different components attributable to various explanatory variables or experimental treatments. This allowed researchers to systematically compare the means of multiple groups and assess the significance of differences, revolutionizing agricultural and biological experimentation, and later finding wide application in economics and other social sciences.

In his seminal book The Design of Experiments (1935), Fisher laid out fundamental principles for conducting valid and efficient experiments, including:

• Randomization: Assigning treatments to experimental units randomly to avoid systematic bias.
• Replication: Repeating treatments on multiple units to estimate variability and increase precision.
• Blocking (Local Control): Grouping experimental units into homogeneous blocks to reduce extraneous variation.

These principles are crucial for establishing causal relationships and are increasingly applied in experimental economics.

Fisher introduced and extensively developed the method of maximum likelihood estimation as a general technique for estimating the parameters of a statistical model. MLE finds the parameter values that make the observed data most probable. It has become a cornerstone of statistical inference and is widely used in econometric modeling. He also defined key properties of estimators like consistency, efficiency, and sufficiency.

Fisher formalized the concept of statistical significance testing, including the use of the p-value. A p-value, in Fisher's framework, is a measure of the strength of evidence against a specified null hypothesis. While the interpretation and use of p-values have been subjects of ongoing debate, Fisher's work laid the groundwork for much of modern hypothesis testing.

Fisher proposed fiducial inference as an alternative approach to statistical inference, distinct from both frequentist and Bayesian methods. While it generated considerable debate and has not been as widely adopted as his other contributions, it reflects his deep thinking on the foundations of statistical reasoning.

Fisher was a leading figure in the modern evolutionary synthesis, which reconciled Darwinian natural selection with Mendelian genetics.

This is his most important work in evolutionary biology. In it, he demonstrated mathematically how continuous variation could arise from the action of multiple discrete genes and how natural selection acting on these genes could lead to evolutionary change. He also introduced Fisher's fundamental theorem of natural selection.

He provided a mathematical explanation for why the sex ratio in most species that reproduce sexually is approximately 1:1.

Fisher made fundamental contributions to population genetics, developing mathematical models to describe gene frequencies in populations and how they change under selection, mutation, migration, and genetic drift.

While Fisher did not directly contribute to economic theory, the statistical tools and principles he developed have been indispensable for the development of modern econometrics and quantitative economic research.

• ANOVA and Regression: ANOVA and its close relative, regression analysis (to which Fisher also contributed), are fundamental tools for economists analyzing relationships between economic variables, testing hypotheses, and forecasting.
• Maximum Likelihood Estimation: MLE is the workhorse for estimating a vast array of econometric models, including those for limited dependent variables (e.g., logit, probit), time series models (e.g., ARIMA, GARCH), and structural models.
• Hypothesis Testing: Fisher's framework for significance testing is widely used by economists to assess the statistical significance of estimated coefficients and to test economic theories.

The principles of experimental design laid out by Fisher are increasingly important in economics, particularly in:

• Experimental Economics: Laboratory experiments designed to test economic theories often rely on Fisherian principles of randomization and control.
• Field Experiments and Program Evaluation: Randomized controlled trials (RCTs), directly inspired by Fisher's work, have become a gold standard for evaluating the impact of economic policies and development interventions.

Fisher's emphasis on rigorous statistical modeling, parameter estimation, and hypothesis testing provided a conceptual and methodological foundation upon which much of modern econometrics has been built. His work helped transform economics into a more empirically grounded and quantitatively sophisticated discipline.

Fisher was a lifelong and prominent advocate of eugenics, the belief in improving the genetic quality of the human population. He argued that in modern societies, there was a tendency for the "less fit" (often equated with lower socioeconomic classes) to have more children than the "more fit" (upper classes), leading to a decline in national ability. He proposed policies such as financial incentives for families of higher socioeconomic status to have more children. This aspect of his work is highly controversial today and is widely condemned for its discriminatory and socially regressive implications. His views on race were also problematic by modern standards.

Fisher received numerous honours for his scientific contributions, including:

• Fellow of the Royal Society (1929)
• Royal Medal (1938) and Darwin Medal (1948) from the Royal Society
• Copley Medal (1955), the Royal Society's highest award
• Knighted by Queen Elizabeth II in 1952.

He held academic positions at University College London (as Galton Professor of Eugenics, 1933–1943) and the University of Cambridge (as Arthur Balfour Professor of Genetics, 1943–1957). After retiring from Cambridge, he moved to Adelaide, Australia, where he continued his research as a senior research fellow at the CSIRO.

Ronald Aylmer Fisher died in Adelaide on 29 July 1962, from complications following surgery for colon cancer.

• Sir Ronald Fisher is unequivocally one of the giants of 20th-century science.
• His contributions to statistics transformed it from a collection of ad hoc methods into a coherent mathematical discipline with profound implications for all empirical sciences.
• His work in evolutionary biology was crucial for establishing the modern synthesis.
• In economics, his indirect influence via the adoption of his statistical methods has been immense. Modern econometrics and quantitative economic analysis would be unimaginable without the tools he developed.
• His strong advocacy for eugenics remains a significant stain on his legacy and requires critical contextualization.

Fisher was a prolific author. His key books include:

• "Statistical Methods for Research Workers" (1925, and many subsequent editions): A highly influential and practical guide that disseminated his statistical techniques (including ANOVA, correlation, regression, chi-squared tests) to a wide audience of researchers across many fields, including economics.
• "The Genetical Theory of Natural Selection" (1930): His seminal work in evolutionary biology.
• "The Design of Experiments" (1935, and many subsequent editions): Laid out the fundamental principles of experimental design (randomization, replication, blocking), which are increasingly applied in economics.
• Statistical Tables for Biological, Agricultural and Medical Research (1938, with Frank Yates)
• The Theory of Inbreeding (1949)
• Statistical Methods and Scientific Inference (1956): A more philosophical work on the foundations of statistical inference, including his views on fiducial probability.

He also published nearly 300 scientific papers. Many of these introduced or developed key statistical concepts like maximum likelihood, sufficiency, and the analysis of variance.

• Statistics
• Analysis of variance (ANOVA)
• Experimental design
• Maximum likelihood estimation
• P-value
• Modern evolutionary synthesis
• Population genetics
• Econometrics
• Eugenics
• Jerzy Neyman
• Egon Pearson
• Karl Pearson