for some defendants. Rossman and his colleagues (1980) also found that, while a smaller fraction of gun-carrying defendants were convicted of felony gun-carrying, the fraction that received prison sentences did increase. These shifts in case processing and the discretionary actions of criminal justice practitioners in Massachusetts are common responses to the adoption of mandatory sentences (see, e.g., Alschuler, 1978).
Pierce and Bowers (1981) used interrupted-time-series techniques and multiple control group comparisons to examine the impact of Bartley-Fox on firearm-related and nonfirearm-related assaults, robbery, and homicide in Boston. They found a statistically significant reduction in gun assaults in March 1975, one month prior to the implementation of the Bartley-Fox law. The authors suggest that the vigorous publicity campaign influenced behavior before the law actually went into effect. The multiple control group comparison consisted of simple percentage change analyses of firearm-related crime rates in 1974 and 1975 for Boston relative to other New England cities, the United States without Massachusetts, the middle Atlantic states, the north central states, and selected cities within a 750-mile radius, including Washington, DC, Baltimore, New York, Philadelphia, Cleveland, and Detroit. Pierce and Bowers (1981) found that the law significantly reduced firearm-related assaults, but produced offsetting increases in nonfirearm-related armed assaults; there was some reduction in firearm-related robberies accompanied by a lesser increase in nonfirearm-related armed robberies; and firearm-related homicides were reduced with no increase in nonfirearm-related homicides. They conclude that the law, in the short term, may have deterred some individuals from carrying or using their firearms, but it did not prevent them from substituting alternative weapons.
Using similar methods, Deutsch and Alt (1977) analyzed police reports of firearm-related assaults, homicide (all types), and armed robbery (including other weapons) for the time period January 1966 through October 1975. The evaluation was designed to detect short-term impacts of the law, as it only included a six-month horizon after the enactment of the law. Deutsch and Alt found a statistically significant 18 percent decrease in gun assaults and a statistically significant 20 percent decrease in armed robberies, but no statistically significant changes in homicide incidents. Hay and McCleary (1979) reanalyzed Deutsch and Alt’s data and suggest that the stochastic components of the time series were not specified correctly and the postintervention time series was too short to permit an accurate specification of the intervention component. Hay and McCleary suggest that the Deutsch and Alt findings are inconclusive. In a rejoinder, Deutsch (1979) critiques the ARIMA model specification choices made by Hay and McCleary in their reanalysis and comments that their research was “wrought with inconsistencies, inaccuracies, and half truths” (p. 327).