Matt Ashby

A quasi-experiment (🇺🇸) found two publicity campaigns (geo-targeted messages broadcast to mobile phones and anti-violence messages stencilled on pavements) had no effect on violent crime. doi.org/10.1111/1745...

Changing the standard for judging police deadly force (🇺🇸) from “reasonable” to “necessary in defense of human life” had no effect on how many people were killed by police (as proponents claimed) or on how many officers were injured (as opponents claimed) doi.org/10.21428/cb6...

Liberating criminology from a narrow focus on offender motivation meant criminologists could also understand that crime is partly caused by opportunities, which has been hugely important in developing effective ways to prevent crime. doi.org/10.1111/1745...

This experiment finds a practitioner or global-south researcher without expensive institutional journal subscriptions can only access about 5% of criminology research. Long past time more researchers (especially in the US) got serious about open access. doi.org/10.21428/cb6...

Useful short summary of research evidence on the limited effect of CCTV (including automated numberplate recognition cameras) on crime and police outcomes. counciloncj.org/wp-content/u...

The decision not to install immobilisers on Kia/Hyundai cars (🇺🇸) led to over 1.1 million extra vehicle thefts over 5 years. Note: unlike other developed countries, the US doesn't require manufacturers to fit cars with immobilisers. www.crimrxiv.com/pub/4u5hwcwg...

When a temporary speed trap (🇦🇺) appears on phone navigation apps (Waze, Google Maps, etc.), average vehicle speed on that road drops by about 4km/h. One for academics still teaching students that offenders don't make rational choices, I guess. 😉 doi.org/10.1007/s112...

@alextrinidad.eurosky.social and other members of esc-enoc.github.io, are thinking of creating a new OA journal in #Criminology under the PCI model. At this stage we are reaching out to see if we could gather 50 colleagues that could commit to help as associate editors. Let us know if interested.

Embedding mental-health clinicians in police control rooms (🇺🇸) was associated with a small drop (about 7%) in police deployments to mental-health calls. Seems like this would have been a good opportunity for a randomised controlled trial, though. doi.org/10.1080/0735...

Repeat victimisation happens to police officers, too, especially when it comes to violent crime. Useful reminder in @policinginsight.bsky.social of the importance of leveraging concentrations of victimisation risk when trying to prevent officers being assaulted. policinginsight.com/feature/opin...

Of 812 articles in the British Journal of Criminology (2014–2024), only 0.2% (two articles in 11 years!) used experimental/quasi-experimental methods. (Quasi-)experiments aren't good for everything, but is UK crim research really using the right methods? doi.org/10.1007/s112...

Mark Rowley hits the nail on the head: “If we're serious about policing London effectively … Why wouldn't we want people who … can connect with every part of one of the world's most globally connected cities? These aren't ideological arguments. They're practical … necessities.” lnkd.in/p/e9XTGmvU

Replacing sodium street lights with LEDs (🇺🇸) led to substantial reductions in night-time property and violent crime outdoors, but the effect only lasted for six months before crime reverted to previous levels. doi.org/10.1007/s109...

For anyone looking for an up-to-date example of the base rate fallacy … 🤦‍♂️

A randomised trial (🇺🇸) of sending police drones to calls at the same time as dispatching officers found the drones decreased both how quickly police arrived at calls and how quickly calls were resolved. (Not yet peer reviewed) doi.org/10.21428/cb6...

An excellent blog post on some of the challenges of using generative AI tools in policing. As so often, it’s the non-technical issues that are the hardest to work through! Definitely worth your time: stephenrussell996702.substack.com/p/counting-c...

Incorporating street networks into geographic profiles of serial homicides produced results that were no more accurate, despite profiles using street networks requiring more work and taking longer. doi.org/10.21428/cb6...

This paper finds that the chances of a person with a criminal conviction (🇺🇸) being charged with a further crime drops rapidly every year afterward conviction, such that after 10 years they're no more likely to reoffend than the population at large. doi.org/10.1111/1745...

This study finds police officers (🇨🇦) perceive dealing with an armed robbery or violent domestic assault in progress as much more dangerous than driving to an emergency call, even though vehicle crashes are the top killer of cops (in 🇨🇦 and elsewhere). doi.org/10.1080/1043...

Join us tomorrow!

More undocumented immigrants moving into a neighbourhood (🇺🇸) is associated with a small *decrease* in violent crime rates and no change in property crime. More legal immigrants moving to an area isn't associated with changes in violent or property crime. doi.org/10.1080/0735...

A hopefully useful (free) opportunity to hear from the statisticians who create our crime statistics on what they're working on. www.eventbrite.co.uk/e/annual-cri...

This huge replication (🇺🇸) of the 'Koper curve' on how long hotspot patrols should last reinforces the original findings: patrols are effective once cops are in a hotspot for 15 mins, after which staying in that area has no extra crime-prevention effect. doi.org/10.1111/1745...

Useful estimates in this paper of how long it takes for crimes of different types of be reported and recorded (🇺🇸), i.e. how long it takes for crime data to be 'stable' enough for research and analysis. For most types, >90% are reported within 14 days. doi.org/10.1080/0741...

'The Westminster government’s contribution to funding domestic undergraduates studying in England fell in real terms from £8.9 billion in 2012-13 to just £3.3bn in 2024-25, a drop of more than 60 per cent, an analysis has found.'

This paper finds the 'iron rule' that most crimes happen in a small number of places applies equally in an African city (Abuja, 🇳🇬) and when measured using data from a door-to-door survey rather than police data (which is limited by under-reporting). doi.org/10.1057/s413...

Previous research has found sending offenders a letter can have a surprisingly big effect on behaviour, but this paper (🇳🇱) found that didn't work to prevent people texting while driving: the letter in this case had no effect on the chance of reoffending. doi.org/10.1080/1561...

This paper (🇨🇱) finds more pedestrians (who are both 'eyes on the street' who might protect against crime, and potential targets of it) doesn't lead to any increase in theft until a critical crowd density is reached, after which theft rises sharply. doi.org/10.21428/cb6...

If you’re an emergency service that’s still encouraging people to use What3Words to locate themselves in an emergency, you might want to consider how likely it is the service will still be running given it’s run by a private company that loses millions every year.