SUMMARY The One Handed use page of the HIG is based on outdated research, specifically http://www.uxmatters.com/mt/archives/2013/02/how-do-users-really-hold-mobile-devices.php An updated version of this research can be found at https://www.uxmatters.com/mt/archives/2017/03/design-for-fingers-touch-and-people-part-1.php It would be nice if the HIG was based on up to date research.