  The advent of social media expands our ability to transmit information and
connect with others instantly, which enables us to behave as "social sensors."
Here, we studied concurrent bursty behavior of Twitter users during major
sporting events to determine their function as social sensors. We show that the
degree of concurrent bursts in tweets (posts) and retweets (re-posts) works as
a strong indicator of winning or losing a game. More specifically, our simple
tweet analysis of Japanese professional baseball games in 2013 revealed that
social sensors can immediately react to positive and negative events through
bursts of tweets, but that positive events are more likely to induce a
subsequent burst of retweets. We also show that these findings hold true across
cultures by analyzing tweets related to Major League Baseball games in 2015.
Furthermore, we demonstrate active interactions among social sensors by
constructing retweet networks during a baseball game. The resulting networks
commonly exhibited user clusters depending on the baseball team, with a
scale-free connectedness that is indicative of a substantial difference in user
popularity as an information source. While previous studies have mainly focused
on bursts of tweets as a simple indicator of a real-world event, the temporal
correlation between tweets and retweets implies unique aspects of social
sensors, offering new insights into human behavior in a highly connected world.
