It is a means for defining an urban region by including the areas from which individuals commute.
The researchers that study daily urban system (DUS) are basically focusing on the transportation planning.
A daily urban system, on the other hand, only show how far away people who commute into a city are living.
It shows how much sprawl has occurred, or how people are living far away from where they commute to everyday due to differences in conditions between the regions.
Researchers looked into the daily urban systems within Randstad to determine if the megalopolis is considered a network city.
Roughly 7 million people live outside of Paris proper, but are easily within the greater Parisian area.