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.
Facebook Post Images. The optimal size for post (shared) images is 1,200 x 630 pixels. These guidelines will help you select and edit your shared images for optimum quality: 1  Recommended upload size is 1,200 x 630 pixels. 2  Will appear with a maximum width of 470 pixels in Facebook feed. 3  Will appear on a Facebook page with a maximum width of 504 pixels.