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.
The answer is obvious of course. Facebook posts should be sent exactly 9 times each day, with nor more than 3 clumped within a 2 hour period. On Wednesdays you should add 2 posts at midday and on Thursday evenings you should skip one. Twitter is 14 times each day between 8:34am and 3:27am, with no more than 3 repeated. Pinterest should be avoided between 5 and 7pm weekdays but can be doubled up on Sunday afternoons, particularly during football season. LinkedIn is more of a weekday 9-5 things since it's business oriented, and you don't want to repeat things very often there either.