Al-Matarneh Mohammad Ata, SattamGamallo Otero, Pablo2018-06-122018-06-122018-05-25Almatarneh S, Gamallo P (2018) A lexicon based method to search for extreme opinions. PLoS ONE 13(5): e0197816. https://doi.org/10.1371/journal.pone.0197816http://hdl.handle.net/10347/16791Studies in sentiment analysis and opinion mining have been focused on many aspects related to opinions, namely polarity classification by making use of positive, negative or neutral values. However, most studies have overlooked the identification of extreme opinions (most negative and most positive opinions) in spite of their vast significance in many applications. We use an unsupervised approach to search for extreme opinions, which is based on the automatic construction of a new lexicon containing the most negative and most positive wordseng© 2018 Almatarneh, Gamallo. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedAtribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/LexiconsSemanticsElectronicsMachine learning algorithmsAlgorithmsMachine learningInformation retrievalSocial mediajournal article10.1371/journal.pone.01978161932-6203open access