J. Scott Armstrong, an emeritus professor of marketing at the Wharton School, died on September 28 due to complications from vascular dementia and Alzheimer’s disease. He was 86.

Born in Philadelphia, Dr. Armstong lived most of his life in the region. He earned two bachelor’s degrees from Lehigh University—one in applied science and the other in industrial engineering, then received a master’s degree in industrial administration from Carnegie Mellon University. After earning his doctorate in management from the Massachusetts Institute of Technology in 1968, Dr. Armstrong joined Wharton’s faculty as an assistant professor in the department of marketing. Four years later, he advanced to the rank of associate professor, and he became a full professor in 1998. He retired from Wharton in 2020 and took emeritus status.

While at Wharton, Dr. Armstrong was internationally recognized for his expertise in forecasting, which is the use of historical data to predict future trends. He held 24 international visiting appointments at 17 universities, including the Stockholm School of Economics (1974-1975), IMD in Lausanne, Switzerland (1980-1981), and the Ehrenberg-Bass Institute at the University of South Australia (2011-2020). Among his achievements, he founded the Journal of Forecasting in 1982, published four books (including the renowned Long-Range Forecasting and Principles of Forecasting: A Handbook for Researchers and Practitioners), and authored hundreds of papers and articles. He was also a founder of the International Symposium on Forecasting and http://www.pollyvote.com/, which was launched in 2004 to help predict the results of U.S. presidential elections. He founded http://www.forecastingprinciples.com/ and http://advertisingprinciples.com/ as ways of learning about evidence-based principles and techniques via the internet. In 2016, he and Kesten Green founded the Iron Law of Regulation website, an evidence-based approach to summarize experimental evidence on the effect of regulations on the general welfare.

Dr. Armstrong’s work was heavily awarded. Social Science Research Network’s measure of “impact on researchers” put him in the top 0.1% of roughly 330,000 researchers listed on the site in 2017, and his book, Persuasive Advertising, was a finalist for the American Marketing Association’s “Best Book in Marketing” in 2011. In 2007, he famously challenged former Vice President Al Gore to a 10-year bet, in which $10,000 from the two would be set aside in escrow as Gore pitted his forecast of how much global temperature would increase during that time against a so-called “naive model,” in which temperature would be expected to stay the same. This famous bet caused Dr. Armstrong to be listed in 2010 as the third most famous college professor in the U.S. by collegestats.org. “Scott was one of the most well-known academics of his time, and he will continue to be remembered for his many scientific contributions,” Wharton Deputy Dean Nancy Rothbard said. “He left an indelible mark on the Wharton community, and he will be missed.”

Dr. Armstrong was also an avid runner who logged countless miles over the course of his life. In high school, he joined a relay team that set a record held for 17 years, and in 2007, he won the 70 and older Philadelphia Broad Street Run.

Dr. Armstrong is survived by his wife, Kay; his daughters, Kathy and Jennifer; their spouses, Chris Gillis and Greg Jackson; and his grandchildren, Peter, Astrid, and Sophie. A memorial service was held on October 29.

Contributions may be sent to the Institute for Justice, a nonprofit, public interest law firm, in Dr. Armstrong’s memory.