TABLE 1—
Overall Synthetic Control Results for Point-of-Sale Comprehensive Background Check (CBC) Laws: Maryland and Pennsylvania, 1995 and 1996
| Firearm |
Nonfirearm |
|||||
| Model | MSPE | Effect, % | Placebo No./Total No. (%)a | MSPE | Effect, % | Placebo No./Total No. (%)a |
| Homicide | ||||||
| Maryland 1996 CBC law | 0.531 | +17.5 | 2/32 (0.06) | 0.406 | +33.2 | 2/33 (0.06) |
| Maryland 1996 CBC law (excluding Baltimore) | 0.440 | +3.1 | 11/32 (0.34) | 0.055 | +10.8 | 4/24 (0.17) |
| Pennsylvania 1995 CBC law | 0.167 | +21.5 | 3/23 (0.13) | 0.057 | −10.0 | 5/19 (0.26) |
| Pennsylvania 1995 CBC law (excluding Philadelphia) | 0.044 | +23.9 | 2/14 (0.14) | 0.027 | +4.1 | 5/15 (0.33) |
| Suicide | ||||||
| Maryland 1996 CBC law | 0.060 | −15.4 | 3/24 (0.125) | 0.053 | −21.8 | 1/32 (0.03) |
| Pennsylvania 1995 CBC law | 0.024 | +5.3 | 4/19 (0.21) | 0.003 | −11.8 | 1/11 (0.09) |
Note. MSPE = mean square predicted error.
a
The placebo results reported are the proportions of control states that had a more extreme placebo effect estimate than the effect actually estimated for the true treated state. We restricted the denominator to the subset of donor states with prelaw MSPEs less than 5 times the treated state’s prelaw MSPE.