Dataharvest 2025 - the European Investigative Journalism Conference

Lots of data and investigative journalism takes place in spreadsheets. Frequently, we want to  perform a task for every row in our spreadsheet. For instance, we may have cells containing:

- Quotes from a speech by a European politician that we want to classify into “Pro-EU”, “Anti-EU” or “Neutral”

- Company annual reports from which we want to extract the ultimate controlling party

- Political ads which we want to sift according to whether they mention immigration, directly or indirectly

In this session, participants will learn to write a custom AppScript function in Google Sheets that will enable them to apply Large Language Models (LLMs) from OpenAI and Anthropic to their spreadsheet data.

By the end, attendees will be able to write a formula like =LLM(A1, “gpt-4o”, “Is this text about immigration?”), then drag it down to apply it to hundreds of rows at once. This will enable us to apply the astonishing natural language capabilities of LLMs en masse to cells within our spreadsheet.

Attendees will acquire the following skills:

- Using AppScript to write custom functions in Google Sheets

- Using LLMs via APIs

- Some basic LLM prompting techniques and tips

- Understanding when an LLM is likely to be reliable (when its output is based entirely on data within the spreadsheet) and when it is more likely to hallucinate (when its output draws on its own limited knowledge of the world)