Distribution of happiness.
(a) Histogram of a tweet’s happiness. The histogram shows the distribution of happiness score per tweet. Tweets with zero happiness score were discarded. Similar to the distribution of average happiness in US cities found in , one can see that more tweets have happiness score above the average. (b) Histogram of a cell’s happiness. The histogram shows the distribution of happiness score per area. Areas with zero happiness score and areas containing less than ten unique users were discarded. It is interesting to note that although the distribution of individual tweets’ happiness is negatively skewed, the distribution of areas’ happiness (i.e. aggregate happiness of these tweets) looks symmetric.