Many third-party figures analyzed by eMarketer, while noting declines in desktop usage, did not account for mobile usage of Facebook. Other firms that use panel-based measurement figures have only just begun to track mobile Facebook usage, making it difficult to differentiate long-term trends in mobile usage from seasonal variance. Figures on Facebook’s mobile usage from many firms suggest strong uptake over the past year. Other survey-based figures suggest that while US time spent on Facebook may be declining among some groups like teens and younger adults—who have historically been very active Facebook users—their usage still falls within the definitions for “active usage” that eMarketer and many firms follow, which is a login or engagement with the platform over the course of a month. Read the rest at eMarketer.