7. Conclusions and future directions
From our study we found that crowdsourced sentiment can be a better predictor of match outcomes than crowdsourced odds. In looking at accuracy and payout, the crowdsourced odds-only (Baseline) approach had the highest accuracy versus the eight sentiment models tested. However, in terms of payout, five of the eight sentiment models had higher returns (Subjective Negative $46.82, Objective Negative $58.65, Objective Positive $382.67, All Objective $816.75 and All Negative $726.65). The three models with returns less than Baseline were all clustered around Subjective Positive (Subjective Positive − $1064.50, All Subjective −$2083.42 and All Positive −$179.36). Of the three, only All Subjective lost money, −$195.54. We believe that crowdsourced sentiment was better at identifying longshot wagers as evidenced by five of the sentiment models. For the other three we found the subjective positiveness harmed the results and believe this to be a reaction to events and overconfidence in club performance, rather than rational prescriptive observation transcribed to tweet sentiment. In looking specifically at the models of All Positive and All Negative sentiments and evaluating the surge/drop of match sentiment versus their club average, we found that this technique led to higher accuracy and payouts for the All Positive model (53.28% accuracy and $3011.20 payout). Conversely, All Negative showed a marked decline in performance (27.87% accuracy and $315.17 payout). This result indicates that positive surges (above average club levels) in tweet sentiment generally lead to better match predictability. Tweet authors recognize some factor in their clubs' performance and express it through tweet sentiment. While we expected a similar result with negative sentiment (e.g., recognize something wrong with the club and expect a loss), this was not the case. However, upon a deeper analysis it appears that tweeters from weaker clubs were purposefully injecting negative sentiment into the feeds of their stronger opponents.