scale of the polarity strength.
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  : Description of individual methods combined in our approach[]{data-label="table:methods"}

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Methodology
===========

Next we present the gold standard datasets used to evaluate our approach, the combined baseline method, the metrics used for evaluation and the experimental setup.

In our evaluation, we use 13 **datasets** of messages labeled as positive, negative and neutral from several domains, including messages from social networks, opinions and comments in news articles and videos. These datasets were kindly shared by the authors of  [@ribeiro2015benchmark]. We only consider those with three classes (positive, negative, and neutral). The number of messages vary from few hundreds to a few thousands. The datasets are usually very skewed, with usually one or two classes outnumbered the majority one by large margins. The median of the average number of phrases pier message is around 2 while the average number of words vary from around 15 to approximately 60. We refer the reader to their work for more details about the datasets. We emphasize that the diversity and amount of different datasets used in our evaluation allow us to accurately evaluate not only the prediction performance of the proposed method, but also measure the extent to which 