=Paper= {{Paper |id=Vol-2421/TASS_overview |storemode=property |title=Overview of TASS 2019: One More Further for the Global Spanish Sentiment Analysis Corpus |pdfUrl=https://ceur-ws.org/Vol-2421/TASS_overview.pdf |volume=Vol-2421 |authors=Manuel Carlos Díaz-Galiano,Manuel García-Vega,Edgar Casasola,Luis Chiruzzo,Miguel García-Cumbreras,Eugenio Martínez Cámara,Daniela Moctezuma,Arturo Montejo Ráez,Marco Antonio Sobrevilla Cabezudo,Eric Tellez,Mario Graff,Sabino Miranda |dblpUrl=https://dblp.org/rec/conf/sepln/Diaz-GalianoVCC19 }} ==Overview of TASS 2019: One More Further for the Global Spanish Sentiment Analysis Corpus== https://ceur-ws.org/Vol-2421/TASS_overview.pdf
Overview of TASS 2019: One More Further for
the Global Spanish Sentiment Analysis Corpus?

 Manuel Carlos Dı́az-Galiano1 , Manuel Garcı́a-Vega1 , Edgar Casasola2 , Luis
Chiruzzo3 , Miguel Á. Garcı́a-Cumbreras1 , Eugenio Martı́nez Cámara4 , Daniela
 Moctezuma5 , Arturo Montejo Ráez1 , Marco Antonio Sobrevilla Cabezudo6 ,
               Eric Tellez7 , Mario Graff7 , and Sabino Miranda7
 1
       Universidad de Jaén, Jaén, España {mcdiaz,mgarcia,magc,amontejo}@ujaen.es
     2
        Universidad de Costa Rica, San José, Costa Rica, edgar.casasola@ucr.ac.cr
        3
          Universidad de la República Montevideo, Uruguay luischir@fing.edu.uy
     4
        Andalusian Research Institute in Data Science and Computational Intelligence
           (DaSCI), Universidad de Granada, España emcamara@decsai.ugr.es
                 5
                     CONACyT-CentroGEO dmoctezuma@centrogeo.edu.mx
                      6
                        Universidade de São Paulo msobrevillac@usp.br
                   7
                      CONACyT-INFOTEC {eric.tellez, mario.graff,
                                sabino.miranda}@infotec.mx


          Abstract. In September 2019, the eighth edition of TASS workshop
          (Task of Sentiment Analysis at SEPLN) was held in Bilbao, Spain as
          part of the first edition of IberLEF (Iberian Languages Evaluation Fo-
          rum), which joined the efforts of the IberEval and TASS workshops. In
          this edition, the natural evolution from previous editions was proposed:
          sentiment analysis at tweet level. It includes two subtasks, monolingual
          and cross-lingual sentiment analysis, with different subsets of the In-
          terTASS corpus (ES-Spain, PE-Peru, CR-Costa Rica, UR-Uruguay and
          MX-Mexico). This paper summarizes the approaches and the results of
          the submitted systems of the different groups for each task.

          Keywords: Sentiment Analysis · Opinion Mining · Social Media.


1        Introduction
After seven editions of the workshop on Semantic Analysis at SEPLN (TASS)
as an independent workshop co-located with the International Conference of
the Spanish Society on Natural Language Processing (SEPLN), TASS has been
incorporated into the Iberian Languages Evaluation Forum (IberLEF)8 . IberLEF
  Copyright c 2019 for this paper by its authors. Use permitted under Creative Com-
  mons License Attribution 4.0 International (CC BY 4.0). IberLEF 2019, 24 Septem-
  ber 2019, Bilbao, Spain.
?
  This work has been partially supported by a grant from the Spanish Government
  under the LIVING-LANG project (RTI2018-094653-B-C21) and the REDES project
  (TIN2015-65136-C2-1-R). Eugenio Martı́nez Cámara was supported by the Spanish
  Government Programme Juan de la Cierva Formación (FJCI-2016-28353).
8
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is the result of the association of some workshops in the Natural Language
Processing (NLP) domain for Spanish and other languages spoken in the Iberian
peninsula, and the aim of joining forces of different NLP research communities in
order to provide a common forum for assessing NLP systems and interchanging
research ideas, issues, challenges and experiences.
    Since the edition of TASS 2017 [3], the main aim is the elaboration of a corpus
of sentiment tweets written in different Spanish variants, in order to provide a
representative corpus of Spanish posts written in microblogs all over the world
and not only of the usage of the Spanish language in Spain. Accordingly, the
International TASS corpus was released for the first time in the edition of 2017,
and it was only composed of tweets written in the Spanish used in Spain. The
second version of InterTASS was released in the edition of TASS 2018 [4], and set
of tweets written in the Spanish used in Perú and Costa Rica were added. The
novelty of the edition of TASS 2019 lies in the incorporation of two new Spanish
variants, namely the Spanish written in social media in Mexico and Uruguay.
    The goal behind the aim of compiling a global Spanish corpus of tweets is to
study the differences among different versions of Spanish, and fostering the cross-
lingual research on the Spanish language. Consequently, the TASS 2019 proposed
two subtasks, specifically a mono-lingual polarity classification task (Subtask 1)
and a cross-lingual polarity classification task (Subtask 2) (see Section 2.1).
    Seven research teams submitted several classification results to the Subtask
1, and four teams submitted to the Subtask 2. The systems submitted go in the
line of the state of the art in similar workshops, and the participants developed
classification systems based on Recurrent Neural Networks, Transformer Net-
works and fine-tunning models built upon BERT [2]. The details of the systems
submitted are described in Sections 2.2 and 2.3.



2   Spanish Semantic Analysis Tasks


The workshop “Sentiment Analysis at SEPLN (TASS)” has been held since 2012,
under the umbrella of the International Conference of the Spanish Society for
Natural Language Processing (SEPLN).
    Spanish is the second language used in Twitter, what calls for the develop-
ment of new language comprehension systems and the opportunity of creation
of resources for NLP and, more specifically, for sentiment analysis.
    Many resources have been developed under TASS tasks. In this edition, we
have completed the InterTASS corpus [4] with Uruguayan and Mexican Spanish
variants. The workshop has been built over 2 general task: monolingual and mul-
tilingual approaches, over combinations of the five different datasets of Spanish
language variants.
    In this section we describe the entire InterTASS corpus and the two proposed
tasks.




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2.1   Corpus datasets

International TASS Corpus (InterTASS) is a corpus released in 2017 [3] that was
updated in 2018 [4]. In this edition, it has been extended with new texts written
in two new Spanish variants: Uruguayan and Mexican.
    Therefore, this last version contains tweets written in five different variants
of Spanish from Spain, Peru, Costa Rica, Uruguay and Mexico, and it exhibits
a large amount of lexical and even structural differences in each variant. In this
edition, participants have had to face this five different variants of Spanish to
train and tests their systems.


Spanish dataset The Spanish dataset was released in 2017 as the first version
of InterTASS. Its contains 3,401 tweets in Spanish by users from Spain, and it
is a subset of a biggest corpus collected from July 2016 to January 2017. Each
tweet was labeled with its level of polarity, which can be positive (p), neutral
(neu), negative (n) and no sentiment tag (none). Each tweet was annotated at
least by three annotators. The dataset was originally split into three datasets
that have been reorganized this year, in order to homogenize all the datasets.
The new partitions contain a training set with 1,126 tweets, a development set
with 569 tweets and a test set with 1,706 tweets. Table 1 shown the general
statistics of Spanish dataset.


Table 1. Number of tweets per partition and class of the Spanish (from Spain) dataset

                                     Training Dev. Test
                             P            354 156 594
                             NEU          140 83 195
                             N            475 266 663
                             NONE         157 64 254
                             Total      1,126 569 1,706




Costa Rican dataset The Costa Rican dataset was created in 2018. It contains
2,363 tweets. The annotation methodology replicated the one used to label the
Spanish dataset. Each tweet was labeled as positive (p), neutral (neu), negative
(n) and no sentiment tag (none). Every tweet was labeled by three annotators.
Agreement was reached for 2,048 tweets. For the extra tweets, two more annota-
tors were required to obtain agreement. The dataset also has been reorganized
in order to homogenize the entire corpus. Table 2 shows the new composition.


Peruvian dataset This dataset is comprised by 3,005 tweets in the Peruvian
Spanish variant. The annotation of the dataset was performed as follows. First,
three annotators labeled all the tweets independently. Then, tweets with total




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   Table 2. Number of tweets per partition and class of the Costa Rican dataset

                                     Training Dev. Test
                             P            221 120 366
                             NEU           91 55 151
                             N            310 143 459
                             NONE         155 72 220
                             Total        777 390 1,196



or partial agreement (with agreement between two annotators at least) were in-
cluded into the dataset. Tweets where annotators totally disagreed were labeled
by two additional annotators. After this, the first annotator decided the label of
the tweets where the disagreement continued. Finally, all tweets were included
into the dataset. This partition has also been re-balanced. Table 3 shows the
distribution of tweets according to classes in the Peruvian Spanish variant.


     Table 3. Number of tweets per partition and class of the Peruvian dataset

                                     Training Dev. Test
                             P            216 105 435
                             NEU          170 163 368
                             N            228 107 485
                             NONE         352 200 176
                             Total        966 575 1,464




Uruguayan dataset The Uruguayan dataset is comprised of 2,857 tweets in
the Uruguayan Spanish variant. The annotation process consisted of two phases.
First, of all three annotators independently labeled all the tweets. After this first
step, two more annotators relabeled the tweets that got three different votes in
the first round. The few tweets that were still ambiguous after this process were
discussed between the annotators in order to get a consensus. Table 4 shows the
distribution of tweets in the Uruguayan Spanish variant.


    Table 4. Number of tweets per partition and class of the Uruguayan dataset

                                     Training Dev. Test
                             P            290 153 469
                             NEU          192 90 290
                             N            367 192 587
                             NONE          94 51     82
                             Total        943 486 1,428




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Mexican dataset The Mexican dataset contains 3,000 tweets in the Mexican
Spanish variant. It was generated through a labeling process done with four
annotators. This labeling process consisted of the following steps: 1) for each
tweet, each annotator assigned a polarity of the set {P, N, NEU, NONE}; 2)
from the labels assigned by all annotators, if there is a predominant label, this
is assigned as the class of the tweet, and 3) in the case of no predominant label,
another annotator intervened to obtain a predominant label for final assignment.
The resulting distribution of tweets can be seen in Table 5.


      Table 5. Number of tweets per partition and class of the Mexican dataset

                                     Training Dev. Test
                             P            313 159 525
                             NEU           79 51 119
                             N            505 252 745
                             NONE          93 48 111
                             Total        990 510 1,500




2.2   Task 1: Monolingual
The main goal of this task is the evaluation of polarity classification systems at
tweet level for tweets written in Spanish in a monolingual environment. That is,
the aim is to evaluate systems designed and trained for each individual variant.
   The submitted systems will have to face up with the following challenges:
 – Lack of context: the source elements are tweets.
 – Informal language: misspelling, emojis and onomatopoeia are common.
 – Multilinguality (local): the datasets have been developed with tweets written
   in the Spanish language spoken in Spain, Peru, Costa Rica, Uruguay and
   Mexico.
 – Generalization: the systems will be assessed with several datasets of tweets
   written in the Spanish language spoken in different countries.
   In this task, the participating teams could only perform monovariety ex-
periments using InterTASS dataset (ES-Spain, PE-Peru, CR-Costa Rica, UR-
Uruguay and MX-Mexico), so five rankings have been prepared, one for each
Spanish variant.

Systems presented Seven teams presented their systems and results for this
first task, whose main features are detailed below.

Atalaya Team [8] System inspired in [9]. Different representations of the data
have been used, such as bag-of-words, bag-of-characters and tweet embeddings
and they have trained robust subword-aware word embeddings and computed




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tweet representations using a weighted-averaging strategy. The novelty of the
system is the use of two data augmentation techniques to deal with data scarcity:
two-way translation augmentation, and a novel technique that generates new
instances by combining halves of tweets.

LaSTUS/TALN Team [1] The system proposes a deep learning approach based
on bidirectional LSTM (biLSTM) models to face both sub-tasks. The tweets
are tokenized keeping emojis and full hashtags and they are transformed in a
embedding process.

GTH-UPM Team [6] The developed system consisted of three classifiers: a sys-
tem based on feature vectors extracted from the tweets, a neural-based classi-
fier using FastText and a deep neural network classifier using contextual vector
embeddings created using BERT (Bidirectional Encoder Representations from
Transformers). The averaged probability of the three classifiers was calculated
to get the final score.

ELiRF-UPV [7] proposed a system focused mainly on employing the encoders
of the Transformer model, based on self-attention mechanisms. The Transformer
model dispenses with convolution and recurrences to learn long-range relation-
ships. They use only the encoder part in order to extract vector representations
that are useful to perform sentiment analysis. They denote this encoding part of
the Transformer model as Transformer Encoder. The results obtained were very
promising, being the first or second ranked system on almost all the Spanish
variants.

The Titans [5] use a bidirectional LSTM based approach to capture information
from both the past and future context followed by an attention layer consisting
of initializers and regularizers.

RETUYT-InCo [10] presents three approaches for classifying the sentiment of
tweets for different Spanish variants. In the first one, they consider multiple vari-
ants to perform a classification of the sentence word vectors mean, performing the
classification through layered fully connected neural networks and support vec-
tor machines. The second approach relies on transfer learning from a pretrained
Spanish BERT. The third approach is based on the use of FastText embeddings
as input to an LSTM neural network. The MLP based approach achieved good
results in monolingual experiments while the BERT based system performed
better in the crosslingual task.

ITAINNOVA [11] explores two different deep learning approaches. The first one
with an embedding-based strategy combined with bidirectional recurrent neural
networks (an architecture that learns the representation of input documents as a
concatenation of self-learned char-embeddings with sequence word-embeddings),
and the second one using the new method of pre-trained BERT. Although the




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performance of the second approach has not been presented as official results, it
is reasonably remarkable and higher than the winner approach.
    Tables 6, 7, 8, 9 and 10 show the results obtained on the Spain, Peru, Costa
Rica, Uruguay and Mexico test datasets respectively. ELiRF-UPV team obtained
the overall best results.

             Table 6. Task-1: Monolingual Sentiment Analysis - Spain

             Team              Macro F1 Macro Precision Macro Recall
             ELiRF-UPV            0.507         0.505            0.508
             Atalaya              0.484         0.533            0.444
             LaSTUS/TALN          0.464         0.47             0.457




             Table 7. Task-1: Monolingual Sentiment Analysis - Peru

              Team             Macro F1 Macro Precision Macro Recall
              Atalaya            0.454          0.462           0.446
              ELiRF-UPV          0.447          0.456           0.439
              RETUYT-InCo        0.438          0.437           0.439




          Table 8. Task-1: Monolingual Sentiment Analysis - Costa Rica

              Team             Macro F1 Macro Precision Macro Recall
              RETUYT-InCo        0.512          0.588           0.454
              ELiRF-UPV          0.496          0.498           0.493
              Atalaya            0.469          0.472           0.467




2.3   Task 2: Crosslingual

The purpose of this task is similar to that of Task 1, but systems must be trained
with one or more Spanish variants and tested with a different Spanish variant.
The Spanish variant of training set had to be different from the evaluation one,
in order to test the dependency of systems on a language.
    Six teams have participated in this task: Atalaya Team, LaSTUS/TALN
Team, GTH-UPM Team, The Titans Team, ITAINNOVA Team and RETUYT-
InCo. The systems are the same as those described in section 2.2.




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           Table 9. Task-1: Monolingual Sentiment Analysis - Uruguay

            Team                 Macro F1 Macro Precision Macro Recall
            ELiRF-UPV              0.515          0.497           0.536
            Atalaya                0.499          0.498           0.499
            GTH-ETSIT-UPM          0.492          0.521           0.466

           Table 10. Task-1: Monolingual Sentiment Analysis - Mexico

            Team                 Macro F1 Macro Precision Macro Recall
            ELiRF-UPV              0.501          0.490           0.512
            GTH-ETSIT-UPM          0.487          0.497           0.477
            RETUYT-InCo            0.486          0.487           0.485



    Tables 11, 12, 13, 14 and 15 show the results obtained on the test sets for
Spanish variants of Spain, Peru, Costa Rica, Uruguay and Mexico respectively.
In three of the five experiment results the Atalaya team obtained the best results,
being the second in the evaluation of Spanish for Costa Rica.
    The values obtained in the evaluation of this task are very similar to those
of Task 1, although slightly lower, which is reasonable as no training data from
the target Spanish variant was allowed.


                       Table 11. Task-2: Crosslingual - Spain

             Team              Macro F1 Macro Precision Macro Recall
             RETUYT-InCo          0.460          0.456           0.465
             LaSTUS/TALN          0.459          0.456           0.462
             Atalaya              0.454          0.433           0.477




3   Conclusions
The 2019 edition of TASS has attracted the participation of 13 systems, seven
for the first task (monolingual sentiment analysis), and six for the second task
(crosslingual). Seven papers with the description of the evaluated systems were
presented. This year, new datasets for the InterTASS corpus have been added,
enlarging this reference corpus for the Spanish sentiment analysis task.
    The submitted systems are in the line the state-of-the-art approaches in other
similar workshops, and most of them are grounded in Deep Learning and the
use of hand-crafted linguistic features.
    As future work, we plan to consolidate the InterTASS corpus to the Spanish-
speaking community, with new challenges for the next year. Moreover, we will




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             Table 12. Task-2: Crosslingual - Peru

  Team                 Macro F1 Macro Precision Macro Recall
  Atalaya                0.474          0.468            0.48
  GTH-ETSIT-UPM          0.456          0.456           0.457
  LaSTUS/TALN            0.448          0.442           0.454




          Table 13. Task-2: Crosslingual - Costa Rica

  Team                 Macro F1 Macro Precision Macro Recall
  GTH-ETSIT-UPM          0.476          0.484           0.469
  Atalaya                0.474          0.479            0.47
  LaSTUS/TALN            0.465          0.472           0.458




           Table 14. Task-2: Crosslingual - Uruguay

  Team                 Macro F1 Macro Precision Macro Recall
  Atalaya                0.514          0.517           0.510
  GTH-ETSIT-UPM          0.481          0.458           0.507
  LaSTUS/TALN            0.469          0.450           0.491




            Table 15. Task-2: Crosslingual - Mexico

  Team                 Macro F1 Macro Precision Macro Recall
  Atalaya                0.473          0.474           0.471
  GTH-ETSIT-UPM          0.471          0.465           0.476
  RETUYT-InCo            0.465          0.455           0.474




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keep working in the development of new corpora and linguistic resources for the
research community.


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