How it works

What the Realtime Factcheck Benchmark is all about.

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How it works


FactBenchmark aims to allow researchers in the field to share check-worthy claims, make evaluations of their veracity and be scored as to their timeliness and accuracy.

We use a Bayesian model to jointly evaluate the truth of claims and (at the same time) the skill of the agents evaluating the claim. As explained on the model page, jointly modeling these two latent variables allows a principled approach to the problem of assigning reputation vs truth. A well known paper that uses a similar approach is How To Grade a Test Without Knowing the Answers.

As per our manifesto all data posted to the benchmark is made public, building up a useful dataset for current and future researchers in the field.


Was that explanation too abstract? Sorry. Let’s spell it out in a more straight forward way.

  • We provide you a series of tagged claims (or articles) and you rate them as true, false, or in between.

We calculate a score for how well your responses correspond to the eventual consensus and provide your account an overall position in the leaderboard. Earlier, more ‘accurate’ responses earn more points. Obviously not everyone agrees on what is true and false which is where our bayesian method for handling consensus kicks in. As explained in more detail below.

  • You can also respond to claims as non-falsfiable, not important or otherwise ‘not checkworthy’.

It is our intention to ensure a steady stream of ‘check worthy’ claims in any benchmark. However we also understand that the decisions as to finding and deciding what claims are ‘worth checking’ is also an important part of the process. For that reason we also include this step in the same transparent decision making process as above and invite any agent to submit check worthy claims and earn a seperate reputation that way.

  • All data is made available, in perpetuity for researchers.

Data is made available in multiple download forms and we hope to build up a useful benchmarking resource. To be 100% clear, some submissions are kept hidden for a 24hr ‘escrow’ period but after that period all data, per our manifesto, is and always will be made available as open data in a non-revokable way.

Our contribution

In the FAQ for Fake News Challenge they write that truth labeling poses several challenges:

  • There exists very little labeled training data of fake versus real news stories.
  • The data that does exist is almost all copyright protected.
  • The data that does exist is extremely diverse and unstructured, making hard to train on.
  • Any dataset containing claims with associated “truth” labels is going to be contested as biased.

It is our intention to address all four of these challenges by providing a unbiased, independent, open, shared data resource of tagged data in collaboration with our members. We also hope to go some way towards addressing the question of bias with a principled Bayesian approach, as described in more detail below.

We wish to acknowledge the great work already done in the area of ‘fake news benchmarks’ - such as the LIAR benchmark dataset, the work done by, claimbuster, and the many others who have been working on the problem of creating research and benchmark data sets - many of whom we are proud to have as members.

It is our hope that, together, we can extend and build on this existing work with this real-time shared open data benchmark.


As with a Kaggle competitions there are two real-time leaderboards that indicate the performance of each of organisation (or ‘agent’) against the two key aspects of the challenge.

  • Finding “check worthy” claims.
  • Evaluating those claims for validity.

Scoring high on either leaderboard requires both timeliness and ‘accuracy’. Specifically agents get higher scores if they post an evaluation which would contribute the most information towards the current consensus for any given claim.

Because the current expected value or ‘consensus’ regarding the veracity or check worthiness of any given claim updates over time, the corresponding points awarded for that item can also change over time. (Benchmarks place an arbitrary time limit around this so as to provide a clear and publishable benchmark, however).

A claim goes through various stages as it moves through the system. On this page we outline the life cycle of a claim, which will also help describe the overall system in more detail.

First, let’s define our terms.

Definition of terms


Our name for accounts on this system. Usually each institution having access to the benchmark will have one agent. FactBenchmark itself also has its own agent, so that any data entered by FactBenchmark is clearly marked as such. All data in the system (including scoring) is attributable to the agent that submitted it or calculated it.


Our name for statements, rumors or quotes that are being evaluated for ‘check-worthiness’ and ‘truthiness’ (or veracity).


The requirements for a claim to be check worthy, are that it is “falsifiable” and “of general interest” as outlined in more detail on the documentation page.


Check-worthy claims can then be evaluated by agents for veracity - they are either ‘true’, ‘false’, or ‘partially true’ as outlined in more detail on the model page. A claim may also be ‘not yet evaluated’, not check-worthy, or of ‘indeterminate veracity’.


A benchmark collects together a set of claims that need to be evaluated, and puts a boundary on when the reputation is updated (the scores on the leaderboard at end of the benchmark is considered to be the ‘outcome’ of the benchmark).

Typical claim life cycle

It should be noted that while it is the intention of this project to allow and even encourage automation, some of these steps require a degree of human curation and judgement. Where needed during the trial, “FactBenchmark” as a project is committed to provide human resourcing (with appropriate level of independence and skills) to ensure that the steps will flow through correctly.

For each claim, the steps of the processing are as follows:

1. Discovery

It is expected that claims will generally be ‘found in the wild’. This may involve detecting a spike of social media activity around a particular rumour and finding a representative tweet for that rumor. Or it may involve parsing a speech from a prominent figure and finding check worthy claims that they make. We expect almost all claims to have one or more supporting sources listed in their ‘evidence’ by way of reaching the threshold for ‘general interest’.

2. Phrasing

Even though claims should ideally have at least one identifiable source it can be hard to find a specific quote with the ideal phrasing for ‘falsifiability’. For that reason we allow that a claim ‘text’ may not exactly match any of its source evidence. It should carry the same basic meaning, or neatly summarize the rumor in such a way as to achieve the threshold for ‘falsifiability’.

3. Submission

Any agent can submit a claim for review at any time. To ensure a sufficient number of check-worthy claims are available for the first benchmarks, FactBenchmark itself will ensure that staff are available to provide a degree of hand curation and discovery of claims if needed. These will be submitted to the system in the same way as any other agent.

4. Annotations to support check-worthy claim

Any time after a submission agents can provide annotations on claims.

Annotations are relatively schema-less and open to interpretation. That said there are three categories of annotation:

  • Annotations that provide support that the claim is check-worthy
  • Annotations that provide support (or refutation) of the claim itself, and
  • Other annotations.

Every annotation is signed by the agent submitting it but as many annotations as desired can be provided at any time.

During this phase it is expected that at least some evidence of support that the claim was made, and that it is of interest would be provided if the claim hopes to get through the next phase.

5. Evaluation for check-worthiness

Agents can also post ‘responses’ to claims at any time. Responses can include the following sections (sometimes one response may include multiple sections):

  • ‘check-worthy’ (‘decline to rate’, ‘better options exist’ or ‘importance’)
  • ‘truth-rating’ (actual estimate of validity)

A “decline to evaluate” response is used when the agent believes the claim is poorly formed, does not have sufficient falsifiability or is not of general interest. Agents are encouraged but not required to provide reasons for a ‘decline to evaluate’ call. Reasons provided may provide useful feedback for others however.

Alternatively a claim can be rated as ‘check-worthy’, and, if desired an ‘importance’ weighting can be provided.

Finally a ‘better options exist’ response is used to indicate that, while this claim is check-worthy there is another claim - that is substantially similar - that is already in existence, that has better phrasing or that in some other way has better support. In such a case the agent may choose to respond with a ‘better options exist’ response on the less important claim. The precise definition of ‘substantially similar’ is deliberately left somewhat loose at this time. Flagging a claim as ‘related’ or ‘duplicate’ does not in any way stop that claim from being evaluated for check-worthiness or validity. However some effort may be put into ensuring that benchmarks do not include too many claims that are ‘substantially similar’ to each other.

6. Acceptance into benchmark

In order to avoid unnecessary work by agents, claims are added to a benchmark only once they reach a threshold for ‘check-worthiness’ required by that benchmark (or more specifically, reach the maximum likelihood estimate for check-worthiness - as described on the model page). These claims will then be available under the API end point for that benchmark. Acceptance into benchmark may also trigger notifications.

Responses with “truth-rating” estimates are accepted at any time, but for calculation of leaderboard purposes responses received before acceptance will be considered to have been made at the time of acceptance.

7. Evaluation for ‘truthiness’

Responses to claims can contain a ‘truth-rating’.

Based on feedback we decided to go for a simple model here. Claims can either be classified as ‘true’, ‘false’, or ‘partially true’. Partially true claims can have a number included, indicating the amount of truth. This should be interpreted as the amount of truth in the claim, as in 50% true, not the confidence of the agent in the truth of the claim. “Liar liar pants on fire” would correspond to a low truthiness value, whereas “Pinocchio” would correspond to a higher truth value.

8. Annotation for validity and support

Agents may choose to provide annotations that provide support for falsity or truth of the statement. In fact they can pretty much share any annotations they like against the claim.

That said it is not the intention of the benchmark to attempt to provide comprehensive tools in this space, as a number of very good tools already exist. As a result we expect that many annotations will merely be pointers to other places with useful information.

9. Benchmark leaderboard

Calculations for agent reputation are a key part of the system, explained in more detail on the model page. The key point to understand is that the reputation is based on the difference between how unlikely the response was at the time it was made and how unlikely it is ‘now’.

A response corresponding to the current consensus has maximum likelihood ‘now’, but to get the most points overall an agent wants to have made that response as early as possible. More specifically, they want to have given their response at a time when the expected likelihood was low (given the consensus at the time).