You'll have to control for a major confounding factor: the number of people per unit area. I would hate to take a walk in a forest that has a population densit

You'll have to control for a major confounding factor: the number of people per unit area. I would hate to take a walk in a forest that has a population density equal to a train station. On the other hand, a train station with a population density equal to a quiet forest might come across as creepy/unsafe.