against sellers in the informal market (through “buy-and-bust” stings), even though affecting the firearms market for offenders, may not be a large enough intervention to produce detectable changes in the levels of either violent crimes or violent crimes with firearms, given the noisiness of these time series and lags in final effects. However, if this enforcement has not affected the money price or the difficulty of acquisition in the secondary market, then it almost certainly has not had the intended effects; thus a cost measure provides a one-sided test. The ADAM (Arrestee Drug Abuse Monitoring) data system provided a potential source of such data at the local level.

Table 4-3 presents a list of hypothesized effects of the major interventions discussed in this chapter. This is more in the nature of a heuristic than a precise classification or prediction. It distinguishes between the two classes of markets and the two forms of acquisition cost (monetary and nonmonetary) in each market. Note again that the principal market for offenders is conceptualized as illegal diversions from retail outlets, such as convicted felons personally lying and buying or using false identification to acquire guns, straw purchasers illegally diverting legally purchased guns, and corrupt licensed dealers falsifying transaction paperwork or making off-the-book sales. The secondary market includes all other informal firearms transfers, such as direct theft, purchases of stolen guns from others, loans or gifts from friends and families, and unregulated sales among private sellers.