Published January 17, 2019 | Version 2.0
Dataset Restricted

PAN19 Authorship Analysis: Style Change Detection

  • 1. University Leipzig
  • 2. Bauhaus-Universität Weimar


This is the data set for the Style Change Detection task of PAN@CLEF 2019.

The goal of the style change detection task is to identify text positions within a given multi-author document at which the author switches. Detecting these positions is a crucial part of the authorship identification process, and for multi-author document analysis in general. Note that, for this task, we make the assumption that a change in writing style always signifies a change in author.


Given a document, we ask participants to answer the following two questions:

  • Was the given document written by multiple authors? (task 1)
  • For each pair of consecutive paragraphs in the given document: is there a style change between these paragraphs? (task 2)

In other words, the goal is to determine whether the given document contains style changes and if it indeed does, we aim to find the position of the change in the document (between paragraphs).

All documents are provided in English and may contain zero up to ten style changes, resulting from at most three different authors. However, style changes may only occur between paragraphs (i.e., a single paragraph is always authored by a single author and does not contain any style changes).


To develop and then test your algorithms, two data sets including ground truth information are provided. Those data sets differ in their topical breadth (i.e., the number of different topics that are covered in the documents contained). dataset-narrow contains texts from a relatively narrow set of subjects matters (all related to technology), whereas dataset-wide adds additional subject areas to that (travel, philosophy, economics, history, etc.).

Both of those data sets are split into three parts:

  • training set: Contains 50% of the whole data set and includes ground truth data. Use this set to develop and train your models.
  • validation set: Contains 25% of the whole data set and includes ground truth data. Use this set to evaluate and optimize your models.
  • test set: Contains 25% of the whole data set. For the documents on the test set, you are not given ground truth data. This set is used for evaluation.

Input Format

Both dataset-narrow and dataset-wide are based on user posts from various sites of the StackExchange network, covering different topics. We refer to each input problem (i.e., the document for which to detect style changes) by an ID, which is subsequently also used to identify the submitted solution to this input problem.

The structure of the provided datasets is as follows:




For each problem instance X (i.e., each input document), two files are provided:

problem-X.txt contains the actual text, where paragraphs are denoted by \n\n.
truth-problem-X.json contains the ground truth, i.e., the correct solution in JSON format:

    "authors": NUMBER_OF_AUTHORS,
    "structure": ORDER_OF_AUTHORS,
    "site": SOURCE_SITE,
    "multi-author": RESULT_TASK1,
    "changes": RESULT_ARRAY_TASK2

The result for task 1 (key "multi-author") is a binary value (1 if the document is multi-authored, 0 if the document is single-authored). The result for task 2 (key "changes") is represented as an array, holding a binary for each pair of consecutive paragraphs within the document (0 if there was no style change, 1 if there was a style change). If the document is single-authored, the solution to task 2 is an array filled with 0s. Furthermore, we provide the order of authors contained in the document (e.g., [A1, A2, A1] for a two-author document), the total number of authors and the Stackoverflow site the texts were extracted from (i.e., topic).

An example of a multi-author document, where there was a style change between the third and fourth paragraph could look as follows (we only list the two relevant key/value pairs here): 

    "multi-author": 1,
    "changes": [0,0,1,...]

A single-author document would have the following form (again, only listing the two relevant key/value pairs):

    "multi-author": 0,
    "changes": [0,0,0,...]



Version 2.0: added validation and test set



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Additional details


  • Eva Zangerle, Michael Tschuggnall, Günther Specht, Martin Potthast, and Benno Stein. Overview of the Style Change Detection Task at PAN 2019. In Linda Cappellato, Nicola Ferro, David E. Losada, and Henning Müller, editors, CLEF 2019 Labs and Workshops, Notebook Papers, September 2019.