Postal density is a measure that contains two  exogenous cost drivers such as geographic and demographic characteristics of the areas served, and endogenous drivers reflecting the quality of delivery service.
Geographic and demographic characteristics both impact postal density.
The quality of delivery service is not correlated with postal density.
A young person is skateboarding down a ramp.
Vrenna ran away without being hurt.
Bayliss was very happy.
the boy shovels
two cats are chasing a soccer ball
The man was taking pictures outside.