In 1996, the ICRG awarded its first grant to Harvard Medical School's Division on Addictions, led by Howard Shaffer, Ph.D., to conduct a meta-analysis of prevalence studies in order to determine a rate of how many people in the U.S. have a gambling problem. The research team examined 120 prevalence studies to gather data for their analysis.
The study's findings indicated that approximately 1.14 percent to 1.60 percent of the adult population could be classified as experiencing pathological problems associated with gambling. These estimates were considered the most accurate at the time and were praised by the National Research Council of the National Academy of Sciences in
their publication Pathological Gambling: A Critical Review (1999) for providing the best current estimates of gambling-related issues in the general adult U.S. population and
The initial study was published in the American Journal of Public Health in 1999, and an updated version was released in 2001 in the Canadian Journal of Public Health.