Average Happiness, 2008-2011 (IMAGE) University of Vermont Caption A graph of average happiness measured over a three year period running from Sept. 9, 2008 to Aug. 31, 2011, created by scientists at the University of Vermont using data from Twitter. Published in the journal PLoS ONE, Dec. 7, 2011. A regular weekly cycle is clear with the red and blue of Saturday and Sunday typically the high points -- and an overall downward trend in 2010 and 2011 is clear. Credit Peter Dodds et al, University of Vermont Usage Restrictions With associated article License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.