Category Archives: WP7

Querylog-based Assessment of Retrievability Bias in Delpher

On March 17, we were invited by the National Library of the Netherlands to present the results of our study on retrievability bias in the Dutch historic newspaper archive.
The research was conducted in collaboration with the WebART project and will be presented at the Joint Conference on Digital Libraries (JCDL) 2016 in Newark, USA, in June 2016.

Summary of the talk:

Search engines are not “objective” pieces of technology, and bias in Delpher’s search engine may or may not harm user access to certain type of documents in the collection. In the worst case, systematic favoritism for a certain type can render other parts of the collection invisible to users. This potential bias can be evaluated by measuring the “retrievability” for all documents in a collection. We explain the ideas underlying the retrievability metric, and how we measured it on the KB Newspaper collection.  We describe and quantify the retrievability bias imposed on the newspaper collection by three different commonly used Information Retrieval models. For this, we investigated how document features such as length, type, or date of publishing influence the retrievability.
We also investigate the effectiveness of the retrievability measure, featuring two characteristics that set our experiments apart from previous studies: (1) the newspaper collection contains noise originating from OCR processing, and historical spelling and use of language; and (2) rather than the simulated queries used in other studies, we use real user query logs including click data. We show how simulated queries differ from real user queries regarding term frequency and prevalence of named entities, and how this affects the results of a retrieval task.


Impact Analysis of OCR Quality on Research Tasks in Digital Archives

We presented our paper on “Impact Analysis of OCR Quality on Research Tasks in Digital Archives” at this year’s International Conference on Theory and Practice of Digital Libraries (TPDL2015).

We describe how humanities scholars currently use digital archives and the challenges they face in adapting their research methods compared to using a physical archive. The required shift in research methods has the cost of working with digitally processed historical documents. Therefore, a major concern for the scholars is the question how much trust they can place in analyses based on noisy representations of source texts.

Based on interviews with humanities scholars and a literature study, we classify scholarly research tasks according to their susceptibility to errors originating from OCR-induced biases. Search results for “Amsterdam”, for example, are likely to be influenced by the confusion of the letters “s” and “f”, especially for material that was created before 1800, when the “long s” was still used.
In order to reduce the impact of such errors, we investigated which kind of data would be required for this and whether or not it is available in the archive.

We describe our study of example research tasks performed on the digital newspaper archive of the National Library of The Netherlands. In this study, we tried to reduce the uncertainty of the results as much as possible with the data publicly available in the archive.

We conclude that the current knowledge situation on the scholars’ side as well as on the tool makers’ and data providers’ side is insufficient and needs to be improved.

Historical Newspapers as “Big Data”

On Tuesday, March 24, 2015, the National Library of The Netherlands organized a symposium on the use of digitized newspapers in the Digital Humanities. The goal of the symposium was to engage information specialists and end users in a discussion with the KB on future possibilities of using the (data in the) digital newspaper archive.

We presented our research ideas on estimating the impact of OCR errors on research tasks.

For more information about the event, please have a look at the report on the event at the  KB website.