Read the paper! | Download the dataset!

FanOutQA is a high quality, multi-hop, multi-document benchmark for large language models using English Wikipedia as its knowledge base. Compared to other question-answering benchmarks, FanOutQA requires reasoning over a greater number of documents, with the benchmark’s main focus being on the titular fan-out style of question. We present these questions in three tasks – closed-book, open-book, and evidence-provided – which measure different abilities of LLM systems.

This repository contains utilities to download and work with the dataset in Python, along with implementations of the evaluation metrics presented in our paper. Alternatively, you can download the dev and test sets in JSON format and generate completions to submit to us for evaluation.

To view the leaderboards and more documentation about how to use this dataset, check out our website at!

Requirements and Installation#

The fanoutqa package requires Python 3.8+.

To work with just the data, use pip install fanoutqa. Use pip install "fanoutqa[all]" and read the following section to include a baseline retriever and evaluation metrics.


To include a baseline BM25-based retriever, use pip install "fanoutqa[retrieval]".

To run evaluations on the dev set, you will need to run a couple more steps:

pip install "fanoutqa[eval]"
python -m spacy download en_core_web_sm
pip install "bleurt @ git+"


  1. Use fanoutqa.load_dev() or fanoutqa.load_test() to load the dataset.

  2. Run your generations.

    1. Use fanoutqa.wiki_search(title) and fanoutqa.wiki_content(evidence) to retrieve the contents of Wikipedia pages for the Open Book and Evidence Provided settings.

  3. Evaluate your generations with fanoutqa.eval.evaluate(dev_questions, answers) (see below for the schema).

Data Format#

To load the dev or test questions, simply use fanoutqa.load_dev() or fanoutqa.load_test(). This will return a list of DevQuestion or TestQuestion, as documented below.

Common Models#

Primitive = bool | int | float | str

class Evidence:
    pageid: int  # Wikipedia page ID
    revid: int  # Wikipedia revision ID of page as of dataset epoch
    title: str  # Title of page
    url: str  # Link to page

Dev Set#

The development set is a JSON file containing a list of DevQuestion objects:

class DevQuestion:
    id: str
    question: str  # the top-level question to answer
    decomposition: list[DevSubquestion]  # human-written decomposition of the question
    answer: dict[str, Primitive] | list[Primitive] | Primitive
    necessary_evidence: list[Evidence]
    categories: list[str]

class DevSubquestion:
    id: str
    question: str
    decomposition: list[DevSubquestion]
    answer: dict[str, Primitive] | list[Primitive] | Primitive  # the answer to this subquestion
    depends_on: list[str]  # the IDs of subquestions that this subquestion requires answering first
    evidence: Evidence | None  # if this is None, the question will have a decomposition

Test Set#

The test set contains a slightly different format, as the answers are not provided. We include links to all the evidence used in the human-written decompositions for our Evidence Provided task.

class TestQuestion:
    id: str
    question: str
    necessary_evidence: list[Evidence]
    categories: list[str]

Wikipedia Retrieval#

To retrieve the contents of Wikipedia pages used as evidence, this package queries Wikipedia’s Revisions API. There are two main functions to interface with Wikipedia:

  • wiki_search(query) returns a list of Evidence (Wikipedia pages that best match the query)

  • wiki_content(evidence) takes an Evidence and returns its content (as of the dataset epoch) as Markdown.

To save on time waiting for requests and computation power (both locally and on Wikipedia’s end), this package aggressively caches retrieved Wikipedia pages. By default, this cache is located in ~/.cache/fanoutqa/wikicache. We provide many cached pages (~9GB) you can prepopulate this cache with, by using the following commands:

mkdir -p ~/.cache/fanoutqa
wget -O ~/.cache/fanoutqa/wikicache.tar.gz
tar -xzf ~/.cache/fanoutqa/wikicache.tar.gz


To evaluate a model’s generation, first ensure that you have installed all the evaluation dependencies (see above).

To use the GPT-as-judge metric, you will need to provide your OpenAI API key. We intentionally do not read the OPENAI_API_KEY environment variable by default to prevent accidentally spending money; you must set the FANOUTQA_OPENAI_API_KEY environment variable instead. You can use export FANOUTQA_OPENAI_API_KEY=$OPENAI_API_KEY to quickly copy it over.

You should record your model/system’s outputs as a list of dicts with the following schema:

  "id": "The ID of the question (see test set schema) this is a generation for.",
  "answer": "The model's generation."

Finally, to evaluate your generations on the dev set, call fanoutqa.eval.evaluate(dev_questions, answers, llm_cache_key="your-model-key"). This will run all of the metrics and return an EvaluationScore object, which has attributes matching the following structure:

  "acc": {
    "loose": 0,
    "strict": 0
  "rouge": {
    "rouge1": {
      "precision": 0,
      "recall": 0,
      "fscore": 0
    "rouge2": {
      "precision": 0,
      "recall": 0,
      "fscore": 0
    "rougeL": {
      "precision": 0,
      "recall": 0,
      "fscore": 0
  "bleurt": 0,
  "gpt": 0

(to access this in this dictionary form, use dataclasses.asdict().)

Test Set Evaluation#

To evaluate your model on the hidden test set, first generate answers for each question in the test set. Your generations should be in the form of a JSONL file, with each line being a JSON object with the following schema for each test question:

  "id": "The ID of the question (see test set schema) this is a generation for.",
  "answer": "The model's generation."

You will also need to write a metadata file for your model. Your metadata file should use this template:

  "name": "The name of your model",
  "authors": "The list of authors, in natural language (e.g. `Andrew Zhu, Alyssa Hwang, Liam Dugan, and Chris Callison-Burch`)",
  "url": "A link to your model's website, if applicable (null otherwise)",
  "citation": "The list of authors and year, in citation format (e.g. `Zhu et al., 2024`)",
  "context": "The context length of the model your system uses (as an int)",
  "is_trained_for_function_calling": "Whether your model was trained for function calling specifically (true/false)",
  "details": "Additional model details (e.g. API model revision or Hugging Face model ID) - optional",
  "closedbook_generations": "YOUR-SYSTEM-NAME.jsonl",
  "openbook_generations": "YOUR-SYSTEM-NAME.jsonl",
  "evidenceprovided_generations": "YOUR-SYSTEM-NAME.jsonl"

Then, fork this repository. Add your generation files to leaderboard-submissions/[SETTING]-generations/YOUR-SYSTEM-NAME.jsonl and your metadata file to leaderboard-submissions/metadata/YOUR-SYSTEM-NAME.json and make a pull request.

If you do not want to release the generations of your model, please email these files to instead and we will add your model to the leaderboards without pushing the generations.

Finally, our GitHub bot will automatically run metrics on the submitted generations and commit a metrics file to leaderboard-submissions/results/YOUR-SYSTEM-NAME.jsonl. If all looks well, a maintainer will merge the PR and your model will appear on the leaderboards!

Additional Resources#

Although this package queries live Wikipedia and uses the Revisions API to get page content as of the dataset epoch, we also provide a snapshot of English Wikipedia as of Nov 20, 2023. You can download this snapshot here (23G) and its index here.


We would like to thank the members of the lab of Chris Callison-Burch for detailed feedback on the contents of this paper and the members of the Northern Lights Province Discord for their participation in our human evaluation. In particular, we would like to thank Bryan Li for his thoughtful suggestions with regards to our human evaluation and other parts of our paper.

This research is supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via the HIATUS Program contract #2022-22072200005. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of ODNI, IARPA, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright annotation therein.