PubMed · 10968736
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D N Cowan. Docs for guns.. https://pubmed.ncbi.nlm.nih.gov/10968736/
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Small, inexpensive, often poorly made handguns known as "Saturday night specials" are disproportionately involved in crime. Maryland banned the sale of Saturday night specials effective January 1, 1990. During the 2 years between the law's passage in 1988 and its effective date, legal handgun sales in Maryland were 34% higher than expected (p = 0.09). Interrupted time-series analysis of age-adjusted homicide rates for 1975-1998 with statistical controls for trends in two neighboring states, social and economic variables, and temporal patterns in Maryland's homicide rates was used to assess the effect of the law. Estimates of the Saturday night special ban effects depended on the assumption made about the timing of the law's effects. Models that assumed a delayed or gradual effect of the Saturday night special ban produced estimates indicating that firearm homicide rates were 6.8-11.5% lower than would have been expected without the Saturday night special ban (p < or =0.05). The model that assumed an immediate, constant change in response to the law showed no law effect, unless an outlier was excluded from the analysis. Excluding this outlier, the model estimated a 15% increase in firearm homicides associated with the Saturday night special ban. None of the models revealed significant law effects on nonfirearm homicides.
A passive ranging technique based on wavefront curvature is used to estimate the ranges and bearings of impulsive sound sources represented by small arms fire. The discharge of a firearm results in the generation of a transient acoustic signal whose energy propagates radially outwards from the omnidirectional source. The radius of curvature of the spherical wavefront at any instant is equal to the instantaneous range from the source. The curvature of the acoustic wavefront is sensed with a three-microphone linear array by first estimating the differential time of arrival (or time delay) of the acoustic wavefront at each of the two adjacent sensor pairs and then processing the time-delay information to extract the range and bearing of the source. However, modeling the passive ranging performance of the wavefront curvature method for a deterministic transient signal source in a multipath environment shows that when the multipath and direct path arrivals are unresolvable, the time-delay estimates are biased which, in turn, biases the range estimates. The model explains the observed under-ranging of small arms firing positions during a field experiment.
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