Duluth at SemEval-2020 Task 12: Offensive Tweet Identification in English with Logistic Regression
Paper · 2020 · Ted Pedersen
Summary
This paper describes the University of Minnesota Duluth entry to the three English subtasks of OffensEval–2020. Task A decides whether a tweet is offensive. Task B decides whether an offensive tweet is a targeted insult. Task C decides whether the target is an individual, a group or some other entity. The author deliberately built a plain baseline. It is a Scikit logistic regression classifier over unigram and bigram features, adapted from an earlier Duluth SemEval-2018 tweet system. It was trained only on the distantly supervised SOLID corpus. SOLID gives each tweet a real-valued score rather than a label, so the author converted scores to classes with a strict cutoff of .8, aiming for high precision. The system ranked near the bottom on Task A and in the middle or lower on Tasks B and C. The main contribution is a manual error analysis. It suggests that the gold labels are noisy and that profanity or in-group slurs are often treated as offensive automatically. This raises doubts about whether the 90%+ scores of the top systems reflect genuine progress in detecting offensive language.
Key points
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Training data:
- SOLID provided 9,089,139 tweets for Task A, 188,974 for Task B and 188,973 for Task C.
- The manually labeled OLID corpus (13,240 train and 860 test tweets) was deliberately left out, because SOLID was seeded from it and it showed inconsistencies in 2019.
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Label thresholds:
- Task A scores had a median of .25 and a standard deviation of .185.
- With a .8 cutoff, only about 4% of tweets (356,811) counted as offensive.
- In Task B, a score below .2 meant "targeted".
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Official results (macro F1, Duluth vs. top system):
Task Duluth Top system Rank A .7713 .92226 79th of 85 B .53816 .74618 34th of 43 C .57437 .71450 24th of 39 -
Task A behaviour:
- Precision on the OFF class was .896.
- Accuracy was .845, against .722 for a majority-class baseline.
- The system missed half (540) of the gold-offensive tweets.
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Error audit:
- The author drew 10 random samples of 10 tweets from the gold-OFF / predicted-NOT cell.
- Each sample held 2–5 tweets whose offensiveness was reasonably doubtful.
- In the shared task as a whole, 59 teams exceeded a macro F1 of .90.
Interesting ideas
- I1. Audit one confusion-matrix cell by hand through repeated random samples, and count how many items have debatable gold labels; this gives a rough estimate of label noise rather than a single anecdote.
- I2. When supervision comes as a continuous confidence score, set a deliberately strict cutoff to obtain a smaller but more precise positive class, accepting lower recall.
- I3. Treat a weak, transparent baseline as a probe, and read near-perfect leaderboard scores as a possible sign that systems are fitting dataset artifacts rather than solving the task.
- I4. Offensiveness depends on who speaks, who is addressed and their social relation, so the same slur can be bonding inside a group and hostile outside it; word-level features cannot capture this.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): Run this protocol on cases where Mova disagrees with a treebank or silver annotation, to tell real parser errors apart from annotation mistakes before training on them.
- I2 (learn): Admit silver trees or frames into training only when witness agreement is well above a bare majority, trading coverage for cleaner data.
- I3 (learn): Include such simple baselines among the negative controls, so that suspiciously high scores on a test set prompt a check for shortcut patterns.
- I4 (frames): Model the speaker, the addressee and the target as roles in a speech-act frame, so that judgments about insults or irony depend on those participants rather than on surface vocabulary.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 worksSocial Sciences · 1,954 worksCommunication · 104 works
🧭 Topics 1Research subjects and languages the work is about.English · 2,379 works
Cite
Cite as Ted Pedersen. 2020. Duluth at SemEval-2020 Task 12: Offensive Tweet Identification in English with Logistic Regression. Proceedings of the Fourteenth Workshop on Semantic Evaluation.
@inproceedings{pedersen2020duluth,
title = {{Duluth at SemEval-2020 Task 12: Offensive Tweet Identification in English with Logistic Regression}},
author = {Ted Pedersen},
booktitle = {Proceedings of the Fourteenth Workshop on Semantic Evaluation},
year = {2020},
doi = {10.18653/v1/2020.semeval-1.255},
url = {https://doi.org/10.18653/v1/2020.semeval-1.255}
}References
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