A Nonparametric Bayesian model for the Multiple Annotators problem

  • Artes-Rodriguez A.
  • G-Moreno P.
  • Perez-Cruz F.

We propose a generative classification algorithm for a multiple annotators problem, in which the training examples have been simultaneously labeled by a set of imperfect annotators. This algorithm allows us to infer the characteristics (sensitivity and specificity) of each annotator, the ground truth of the training set and build a classifier for test examples. In addition, we consider that the performance of the annotators can be in-homogeneous across the instance space due to several factors like his past experience with similar examples. To capture this behavior, our algorithm uses a Dirichlet Process Mixture Model to divide the instance space in different areas across which the annotators are consistent and resort to variational inference to approximate the posterior of the parameters of the model. Several experiments with synthetic and real databases are performed to prove that the method exhibits high accuracy outperforming state-of-the-art algorithms. In addition, the method offers an interpretable solution and provides an estimation of the performance of the annotators in each of the components, allowing to better understanding the decision process undertaken by the annotators.

Recent Publications

January 01, 2019

Friendly, appealing or both? Characterising user experience in sponsored search landing pages

  • Bron M.
  • Chute M.
  • Evans H.
  • Lalmas M.
  • Redi M.
  • Silvestri F.

© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Many of today's websites have recognised the importance of mobile friendly pages to keep users engaged and to provide a satisfying user experience. However, next to the experience provided by the sites themselves, ...

January 01, 2019

Analyzing uber's ride-sharing economy

  • Aiello L.
  • Djuric N.
  • Grbovic M.
  • Kooti F.
  • Lerman K.
  • Radosavljevic V.

© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Uber is a popular ride-sharing application that matches people who need a ride (or riders) with drivers who are willing to provide it using their personal vehicles. Despite its growing popularity, there exist ...

January 01, 2019

The paradigm-shift of social spambots: Evidence, theories, and tools for the arms race

  • Cresci S.
  • Petrocchi M.
  • Pietro R.
  • Spognardi A.
  • Tesconi M.

© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Recent studies in social media spam and automation provide anecdotal argumentation of the rise of a new generation of spambots, so-called social spambots. Here, for the first time, we extensively study this novel ...