Matt Ashby
@mattashby.com
I help people use data to reduce crime. Associate Professor, Crime Science, UCL. Former police officer.
🌐: mattashby.com
🌐: mattashby.com
🙄 the government is again raising penalties (this time for worrying livestock) “as a deterrent”. This will have zero deterrent effect because there’s almost no chance of prosecution if your dog attacks a sheep.
📢 Increasing the likelihood of punishment can deter, increasing severity probably won’t.
📢 Increasing the likelihood of punishment can deter, increasing severity probably won’t.
December 26, 2025 at 6:14 PM
🙄 the government is again raising penalties (this time for worrying livestock) “as a deterrent”. This will have zero deterrent effect because there’s almost no chance of prosecution if your dog attacks a sheep.
📢 Increasing the likelihood of punishment can deter, increasing severity probably won’t.
📢 Increasing the likelihood of punishment can deter, increasing severity probably won’t.
A lovely Christmas Day walk in some amazing light.
December 25, 2025 at 7:28 PM
A lovely Christmas Day walk in some amazing light.
Happy Christmas!
(This picture is actually from January this year, but we can still dream of a white Christmas.)
(This picture is actually from January this year, but we can still dream of a white Christmas.)
December 24, 2025 at 3:00 PM
Happy Christmas!
(This picture is actually from January this year, but we can still dream of a white Christmas.)
(This picture is actually from January this year, but we can still dream of a white Christmas.)
Useful review of evidence on what works, what doesn’t and what’s promising in using AI in policing. Although the speed of AI development means many emerging technologies haven’t been properly evaluated yet.
Browse all journals
Browse all journals
doi.org
December 23, 2025 at 3:03 PM
Useful review of evidence on what works, what doesn’t and what’s promising in using AI in policing. Although the speed of AI development means many emerging technologies haven’t been properly evaluated yet.
Companies sell AI-based software to automatically review police body-worn video and flag potential misconduct. This study (🇺🇸) found officers are more likely to accept automated flagging if the system also emails supervisors when it finds good conduct.
Does automated feedback impact the acceptability of AI-generated police body worn camera review? An implementation science natural experiment
The diffusion of innovations in policing has often been hindered by barriers to implementation and officer acceptance, which can derail an innovation regardless of its validity or effectiveness.…
www.crimrxiv.com
December 22, 2025 at 3:01 PM
Companies sell AI-based software to automatically review police body-worn video and flag potential misconduct. This study (🇺🇸) found officers are more likely to accept automated flagging if the system also emails supervisors when it finds good conduct.
Reposted by Matt Ashby
Christmas movie? Yes.
Terrorism movie? No.
Thanks for coming to my TED talk.
Terrorism movie? No.
Thanks for coming to my TED talk.
December 20, 2025 at 11:55 PM
Christmas movie? Yes.
Terrorism movie? No.
Thanks for coming to my TED talk.
Terrorism movie? No.
Thanks for coming to my TED talk.
‘Nudge’-based signs encouraging people to lock their bikes at a railway station (🇯🇵) increased how likely people were to do so. This might seem obvious, but some previous research has found signs often aren’t good at changing victim behaviour.
Impact of Antitheft Nudging Signage on Bicycle Owners’ Locking Behavior: A Quasi-Experimental Study in Rural Japan - Ai Suzuki, Takahito Shimada, 2025
This study tested the effectiveness of a nudge-based intervention aimed at encouraging cyclists to lock their bicycles, thereby reducing theft risk in nonurban ...
doi.org
December 19, 2025 at 3:06 PM
‘Nudge’-based signs encouraging people to lock their bikes at a railway station (🇯🇵) increased how likely people were to do so. This might seem obvious, but some previous research has found signs often aren’t good at changing victim behaviour.
Citizens (🇬🇧) greatly overestimate the frequency of bribery in UK businesses: 43% of people think bribery in UK business happens ‘very/fairly often’ but only 3% of businesses were asked for or gave a bribe in the past year.
www.gov.uk/government/p...
www.gov.uk/government/p...
December 18, 2025 at 3:03 PM
Citizens (🇬🇧) greatly overestimate the frequency of bribery in UK businesses: 43% of people think bribery in UK business happens ‘very/fairly often’ but only 3% of businesses were asked for or gave a bribe in the past year.
www.gov.uk/government/p...
www.gov.uk/government/p...
People (in 30 countries) are more likely to co-operate with police if they think police make fair decisions and treat people with respect. In most countries that's more-important in explaining co-operation than police effectiveness or legal duties to obey.
doi.org/10.1111/1745...
doi.org/10.1111/1745...
doi.org
December 17, 2025 at 3:03 PM
People (in 30 countries) are more likely to co-operate with police if they think police make fair decisions and treat people with respect. In most countries that's more-important in explaining co-operation than police effectiveness or legal duties to obey.
doi.org/10.1111/1745...
doi.org/10.1111/1745...
Some students cheat on essays using AI or by paying someone to write for them. But the answer isn’t “severe penalties”, it’s to redesign assessments so it’s harder to cheat.
Too many lecturers set essays that are easy to cheat on and then moan that students cheat.
www.bbc.co.uk/news/article...
Too many lecturers set essays that are easy to cheat on and then moan that students cheat.
www.bbc.co.uk/news/article...
Essay cheating at universities an 'open secret' despite new law
An essay mill owner says he's made millions, while an ex-lecturer says he quit due to rife cheating.
www.bbc.co.uk
December 17, 2025 at 10:08 AM
Some students cheat on essays using AI or by paying someone to write for them. But the answer isn’t “severe penalties”, it’s to redesign assessments so it’s harder to cheat.
Too many lecturers set essays that are easy to cheat on and then moan that students cheat.
www.bbc.co.uk/news/article...
Too many lecturers set essays that are easy to cheat on and then moan that students cheat.
www.bbc.co.uk/news/article...
Training police (🇺🇸) on procedural-justice techniques (e.g. explaining the rationale for police actions) led to improvements in just treatment of people stopped, with the effect not varying by ethnicity of the person.
(Note, though, small sample size)
(Note, though, small sample size)
doi.org
December 16, 2025 at 3:01 PM
Training police (🇺🇸) on procedural-justice techniques (e.g. explaining the rationale for police actions) led to improvements in just treatment of people stopped, with the effect not varying by ethnicity of the person.
(Note, though, small sample size)
(Note, though, small sample size)
Police (🇬🇧) retrospective facial recognition system (e.g. comparing CCTV to mugshots) almost always identifies right suspect but is more often wrong with non-White suspects. Home Office is buying new software that’s equally effective across ethnicities.
Facial recognition technology tests: National Physical Laboratory
Independent testing of facial recognition algorithms commissioned by the Home Office.
www.gov.uk
December 15, 2025 at 3:00 PM
Police (🇬🇧) retrospective facial recognition system (e.g. comparing CCTV to mugshots) almost always identifies right suspect but is more often wrong with non-White suspects. Home Office is buying new software that’s equally effective across ethnicities.
Half of people arrested by police in London who did not have an ADHD diagnosis tested positive on an ADHD screening test after arrest, driven by 60% positive tests among those arrested for drugs offences (for other offence types it was <20% positive).
Neurodiversity in Custody: Screening Results for ADHD and Autistic Traits in Individuals Arrested by the London Metropolitan Police
Background Previous studies have identified high rates of attention-deficit/hyperactivity disorder (ADHD) and autism in incarcerated populations. Despite such findings and the potential benefits of…
doi.org
December 12, 2025 at 3:04 PM
Half of people arrested by police in London who did not have an ADHD diagnosis tested positive on an ADHD screening test after arrest, driven by 60% positive tests among those arrested for drugs offences (for other offence types it was <20% positive).
Reposted by Matt Ashby
“The narrative is ‘rape gangs’ roaming the streets, targeting girls,” he added. “That does happen, but the majority of the crimes that are committed against children are done by people that they know.”
The report also found that child sexual abuse is increasingly happening wholly or partly online
The report also found that child sexual abuse is increasingly happening wholly or partly online
December 11, 2025 at 11:00 AM
“The narrative is ‘rape gangs’ roaming the streets, targeting girls,” he added. “That does happen, but the majority of the crimes that are committed against children are done by people that they know.”
The report also found that child sexual abuse is increasingly happening wholly or partly online
The report also found that child sexual abuse is increasingly happening wholly or partly online
6–15 min police patrols (🇧🇪) every 24h were associated with longest crime-free period after patrols, relative to longer patrols. It’s an observational study, not an experiment, but suggests patrols can have an effect even below 15-min Koper-curve limit.
Short infrequent police stops maximize crime-free time at street segments: Revisiting the Koper curve to establish optimal police dosage - Christophe Vandeviver, Philipp M Dau, Matthew Bland, Stephanie Van De Walle, Maite Dewinter, Frank Witlox, Tom Vander Beken, 2025
Establishing optimal police dosage is central to evidence-based policing. The current consensus is that 15-minute patrols represent the optimal level of such do...
doi.org
December 11, 2025 at 3:01 PM
6–15 min police patrols (🇧🇪) every 24h were associated with longest crime-free period after patrols, relative to longer patrols. It’s an observational study, not an experiment, but suggests patrols can have an effect even below 15-min Koper-curve limit.
This paper introduces an interesting way of comparing violence between countries: the average number of days of life lost to homicide. In the UK it's ~3.4 million total days of life lost to homicide per year, or ~70 minutes off the average British life.
doi.org/10.1177/1088...
doi.org/10.1177/1088...
Sage Journals: Discover world-class research
Subscription and open access journals from Sage, the world's leading independent academic publisher.
doi.org
December 10, 2025 at 3:03 PM
This paper introduces an interesting way of comparing violence between countries: the average number of days of life lost to homicide. In the UK it's ~3.4 million total days of life lost to homicide per year, or ~70 minutes off the average British life.
doi.org/10.1177/1088...
doi.org/10.1177/1088...
Interesting review of research into issues faced by rural police.
Some obvious eg isolation from backup.
Some less so eg community expectation they can bring problems, including non-police problems, to officers 24/7 because they know officer personally.
doi.org/10.1177/0032...
Some obvious eg isolation from backup.
Some less so eg community expectation they can bring problems, including non-police problems, to officers 24/7 because they know officer personally.
doi.org/10.1177/0032...
Sage Journals: Discover world-class research
Subscription and open access journals from Sage, the world's leading independent academic publisher.
doi.org
December 9, 2025 at 3:03 PM
Interesting review of research into issues faced by rural police.
Some obvious eg isolation from backup.
Some less so eg community expectation they can bring problems, including non-police problems, to officers 24/7 because they know officer personally.
doi.org/10.1177/0032...
Some obvious eg isolation from backup.
Some less so eg community expectation they can bring problems, including non-police problems, to officers 24/7 because they know officer personally.
doi.org/10.1177/0032...
Deploying police to optimal points between calls (what ambulance services calls ‘standby’) could reduce emergency response times, relative to random patrol.
Note this is based on computer simulations rather than a real-world test, so treat with caution.
doi.org/10.21428/cb6...
Note this is based on computer simulations rather than a real-world test, so treat with caution.
doi.org/10.21428/cb6...
The Effect of Police Deployment Strategy on Emergency Response Times: An Agent-based Modelling Investigation
This study investigates the impact of three police deployment strategies on emergency response times using agent-based modelling (ABM). Specifically, it evaluates the effectiveness of random patrol,…
doi.org
December 8, 2025 at 3:03 PM
Deploying police to optimal points between calls (what ambulance services calls ‘standby’) could reduce emergency response times, relative to random patrol.
Note this is based on computer simulations rather than a real-world test, so treat with caution.
doi.org/10.21428/cb6...
Note this is based on computer simulations rather than a real-world test, so treat with caution.
doi.org/10.21428/cb6...
Not, perhaps, London Underground’s most useful train arrivals board.
December 6, 2025 at 3:30 PM
Not, perhaps, London Underground’s most useful train arrivals board.
Review of research into the effects on children of witnessing a parent's arrest recommends planning arrests to avoid children being present if possible (which it won't always be) and searching/handcuffing away from children. Hopefully things agencies are already doing.
doi.org/10.1177/1524...
doi.org/10.1177/1524...
Sage Journals: Discover world-class research
Subscription and open access journals from Sage, the world's leading independent academic publisher.
doi.org
December 5, 2025 at 3:04 PM
Review of research into the effects on children of witnessing a parent's arrest recommends planning arrests to avoid children being present if possible (which it won't always be) and searching/handcuffing away from children. Hopefully things agencies are already doing.
doi.org/10.1177/1524...
doi.org/10.1177/1524...
This study of where officers (🇺🇸) chose to patrol between calls found no relationship at all with where crime was most concentrated.
The lesson for police leaders: don’t assume your cops know where to patrol if you haven’t given them clear guidance.
The lesson for police leaders: don’t assume your cops know where to patrol if you haven’t given them clear guidance.
Using automated vehicle locator data to classify discretionary police patrol across space
Place-based policing strategies assume officers have sufficient discretionary time to engage in proactive crime prevention activities, yet little research examines the spatial distribution of…
doi.org
December 4, 2025 at 3:03 PM
This study of where officers (🇺🇸) chose to patrol between calls found no relationship at all with where crime was most concentrated.
The lesson for police leaders: don’t assume your cops know where to patrol if you haven’t given them clear guidance.
The lesson for police leaders: don’t assume your cops know where to patrol if you haven’t given them clear guidance.
Reposted by Matt Ashby
January tickets to our #CM150 exhibition are being snapped up quickly, but everyone seems to be too busy with Christmas shopping for the December ones. There's still good availability on 9-11 & 17 at www.eventbrite.co.uk/e/metropolit... if the #truecrime fan in your life needs an early present ...
Metropolitan Police Museum Gallery Tour
Visit us to learn more about the history of the Metropolitan Police at our Special Exhibition: 150 Years of The Crime Museum
www.eventbrite.co.uk
December 4, 2025 at 11:57 AM
January tickets to our #CM150 exhibition are being snapped up quickly, but everyone seems to be too busy with Christmas shopping for the December ones. There's still good availability on 9-11 & 17 at www.eventbrite.co.uk/e/metropolit... if the #truecrime fan in your life needs an early present ...
I've banged this drum before, but …
Academics, I beg you: please write article titles/abstracts in plain English so people beyond your sub-discipline understand them. Especially if the article is about harm caused by exclusionary language!
(📷 original vs ChatGPT re-write)
Academics, I beg you: please write article titles/abstracts in plain English so people beyond your sub-discipline understand them. Especially if the article is about harm caused by exclusionary language!
(📷 original vs ChatGPT re-write)
December 3, 2025 at 3:02 PM
I've banged this drum before, but …
Academics, I beg you: please write article titles/abstracts in plain English so people beyond your sub-discipline understand them. Especially if the article is about harm caused by exclusionary language!
(📷 original vs ChatGPT re-write)
Academics, I beg you: please write article titles/abstracts in plain English so people beyond your sub-discipline understand them. Especially if the article is about harm caused by exclusionary language!
(📷 original vs ChatGPT re-write)
Police-led lessons on drugs law (e.g. the wide definition of drugs 'supply' in English law) that used procedural-justice principles (fairness, dialog, respect) led to a sustained increase in perceptions of police fairness relative to a control group.
doi.org/10.21428/cb6...
doi.org/10.21428/cb6...
Police in the Classroom: A Three-Wave Cluster-Randomized Controlled Trial
Adolescents’ perceptions of police legitimacy are central to the effective functioning of the legal system. When young people see the police as trustworthy and legitimate, they are more likely to…
doi.org
December 2, 2025 at 3:02 PM
Police-led lessons on drugs law (e.g. the wide definition of drugs 'supply' in English law) that used procedural-justice principles (fairness, dialog, respect) led to a sustained increase in perceptions of police fairness relative to a control group.
doi.org/10.21428/cb6...
doi.org/10.21428/cb6...
Excellent Home Office analysis of what police (🏴🏴) spend their time doing. An essential benchmark if you’re interested in police reform, have ever complained about what police (don’t) do, or if you teach policing to undergrads.
Police Activity Survey
Cookies on GOV.UK
www.gov.uk
December 1, 2025 at 3:01 PM
Excellent Home Office analysis of what police (🏴🏴) spend their time doing. An essential benchmark if you’re interested in police reform, have ever complained about what police (don’t) do, or if you teach policing to undergrads.