Dataharvest 2026 - the European Investigative Journalism Conference

This talk will show the methodology behind The Guardian’s exclusive investigation into properties advertised as tourist destinations on Airbnb and Booking.com located in Israeli settlements that are illegal under international law. The Guardian found 760 rooms being advertised in hotels, apartments, and other holiday rentals in illegal Israeli settlements in the West Bank, as NGOs and activists warned that these companies are violating international law and profiting from war crimes.

In their investigation, they used geospatial tools, like PostGIS and QGIS, to localise accommodations on a specific geographical area, and to join these accommodations with shapefiles representing the borders of illegal settlements to identify those based within settlement boundaries. Using OSINT methods and Google Sheets, they designed a methodology to solve data challenges like duplicate and multi-platform listings, and listings with approximate locations.

In this session, attendees will come up with a robust methodology to find tourist accommodations in any geographical area, so they can reproduce the method for new stories.

Police work is notoriously difficult to investigate. While police actions directly affect fundamental rights and guide politics and law-making, official data on their influence is scarce.

In this session, we will share some tools and methodologies on how to investigate the police sources. We will draw on more than ten years of investigations into different aspects of police violence and state abuse of power in Germany. We will also show how the data-driven journalism tools can help to make the underlying structures more visible, and present our recent investigation into police unions in Germany: who they are, want they stand for and how they influence the public debate and politics. We pieced together data from different sources and combined it with investigative journalism to draw the full picture.

We want to show how it is possible to do a data-driven investigative story despite missing data. We will focus on the following questions:

- How to build your own datasets when no official statistics exist? Which public data sources about the police are available? Which data can we get from ministry inquiries? What about social media?
- How to clean up, classify and analyze the data? Which tools are helpful in combining manual and automated workflows?
- How to tell a complex data-driven story without this one headline? What are judicial and editorial hurdles when publishing a sensitive topic?
- What can investigative and data journalists gain from close collaboration? What worked well? What would we do differently?