Selection bias occurs when the association between exposure and health outcome is different for those who complete a study compared with those who are in the target population. Sources of selection bias. Selective survival and losses to follow-up After enrollment of subjects and collection of baseline data there is
NUMBER OF PUBLIC PHOTOS UPLOADED IN 2013. - 680 million, - 56.7 million per month in average, - 1.86 million per day in average. NUMBER OF PUBLIC PHOTOS UPLOADED IN 2012. - 556 million, - 46.3 million per month in average, - 1.52 million per day in average. NUMBER OF PUBLIC PHOTOS UPLOADED IN 2011. - 575 million, - 47.9 million per month in average, - 1.57 million per day in average.
Total number of mobile Facebook users: 1,126,000,000: Increase in Facebook users from 2014 to 2016: 13.2 %: Total number of minutes spent on Facebook each month: 648,000,000: Percent of all Facebook users who log on in any given day: 48 %: Average time spent on Facebook per visit: 18 minutes: Total number of Facebook pages: 78,200,000: Facebook Demographics: Data