Context information is not included because it is not clear which regions or states the USA sample represents. The USA data was based on the MET video project. Many background information are unknown/unavailable to the authors.
USA
Principal investigator: Prof. KO Yue On, Jamesemail: jamesko@eduhk.hk
Homepage: https://repository.eduhk.hk/en/persons/yue-on-james%E9%AB%98%E8%A3%95%E5%AE%89-ko