The experiments are described in detail, leading to this conclusion:
Criminology: Can the can, from the Nov. 20 print edition of The Economist.
The idea that graffiti-spraying and other forms of low-level delinquency promote further bad behaviour has now been tested experimentally.
A place that is covered in graffiti and festooned with rubbish makes people feel uneasy. And with good reason, according to a group of researchers in the Netherlands. Kees Keizer and his colleagues at the University of Groningen deliberately created such settings as a part of a series of experiments designed to discover if signs of vandalism, litter and low-level lawbreaking could change the way people behave. They found that they could, by a lot: doubling the number who are prepared to litter and steal.
“The message for policymakers and police officers is that clearing up graffiti or littering promptly could help fight the spread of crime.”
Think about this the next time you drive through one of New Albany's myriad slumlord protection districts, and consider another year's passage without meaningful reform amid the absence of money that might be devoted to police and fire protection, as well as pro-active efforts to enforce ordinances and keep the city's neighborhoods clean.