"The Providence Fire Department Staffing Study in 1990-1991 determined that the costs of adding a fourth person to three-person companies was offset by lower injury costs. The problem which prompted this research project was that while an actuary analyzed the study data from an economic standpoint, the data were never analyzed from the perspective of firefighter safety. As a result, the full implications of the study, in terms of firefighter safety, were not known. The purpose of this research was to examine the study data and determine what effect increased staffing had on firefighter safety. The historical research method was used."
United States Fire Administration: http://www.usfa.fema.gov/