I'm not sure you read through the replies

so I'll reiterate my issue with the study that was cited

it is comparing 2 different police forces
UPenn
and PPD
as well as 2 different demographics
Univeristy City residents
and West Philly residents

IMO, it is counter intuitive to say there is less crime on UPenn's campus

*because of the number of security officers inside their perimeter*

considering the employment, income, and other societal factors of those demographics

as well as the differences in law enforcement tactics of the 2 different agencies

could also, easily be an explanation for lower crime rates

a better comparison would be 2 metro areas with similar residential demographics

but one having a higher officer per capita

I'm sure that would result in more 'crimes'

other wise they wouldn't have a need for more officers