The essential distinction between the Fundamental Diagram Approach (FDA) and Kerner’s three-phase theory (KTPT) is the existence of a unique gap–speed (or flow–density) relationship in the former class. In order to verify this relationship, empirical data are analyzed with the following...

The freemium pricing model has become mainstream in the software industry. A large user base can induce positive network effects while expanding security risks associated with unpatched users. This study explores a two-stage decision problem faced by software vendors that involves a freemium...