time series

Why you can't identify changes in crime by comparing this month to last month

This post first appeared on the Social Research Association blog. Understanding if some event is associated with a change in the frequency of crime is a common question, both in practice and in research.

Chart: Stop and search has fallen, arrests from searches less so

Police can search people they suspect of having prohibited items such as drugs or weapons. Since 2011, searches have decreased by 70%. Only 12% of searches lead to arrest, but this is increasing – total arrests from searches have decreased only 38% since 2011, suggesting police are getting better at targeting offenders.

Chart: Stop and search has fallen, arrests from searches less so

Police can search people they suspect of having prohibited items such as drugs or weapons. Since 2011, searches have decreased by 70%. Only 12% of searches lead to arrest, but this is increasing – total arrests from searches have decreased only 38% since 2011, suggesting police are getting better at targeting offenders.