So . . . I was walking back from the home of Megan McArdle and Peter Suderman and instead of doing the normal thing and taking Q Street west to 5th and then walking south, I wanted to take a shortcut by walking south on North Capitol to then cut southwest on New York. But then lo and behold right by Catania Bakery a couple of dudes ran up from behind, punched me in the head, then kicked me a couple of times before running off. Once, years ago, in Amsterdam a guy threatened me with a knife and took my money. These guys took nothing, and just inflicted a bit of pain. All things considered the threaten/rob model of crime seems a lot more beneficial to both parties than the punch-and-run model. But I guess it takes all kinds.
To offer a policy observation, higher density helps reduce street crime in an urban environment in two ways. One is that in a higher density city, any given street is less likely to be empty of passersby at any given time. The other is that if a given patch of land has more citizens, that means it can also support a larger base of police officers. And for policing efficacy both the ratio of cops to citzens and of cops to land matters. Therefore, all else being equal a denser city will be a better policed city.
That said, as a matter of personal ethics you really shouldn’t run around punching random dudes in the back of the head irrespective of the prevailing level of population density or policing.