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This paper uses a surge in stop and search operations following a high-profile murder to look at their effect on recorded crime. Difference-in-difference estimates using detailed geocoded data at the street-level suggest a doubling to trebling of the number of searches in streets close to the place of the murder. IV estimates on the effects of stops and searches on crime suggest little effect on property crime, weapons offences and violent crime or drug offences. Some specifications find reductions in anti-social behaviour, suggesting that any effects on crime are due to an increased police presence on the streets.

Summary We consider two econometric problems when investigating the effect of family size on labour market outcomes using the popular twin birth instrument. The first is the potential for omitted variable bias caused by the fact that fertility treatments are linked to twin births and are typically unobserved. We present estimates that are corrected for this bias and find that it is comparatively small. Second, we show that the effects of twin-birth-induced variation in family size, as well as characteristics of the compliers, varies substantially with time passed since birth, which has consequences for the interpretation of estimates across samples and time.