Metaculus FAQ

Basics

Metaculus Questions

Question Resolution

Predictions

Scoring

Metaculus Journal

Forecasting Causes

Miscellany

Basics

What is Metaculus?

Metaculus is an online forecasting platform and aggregation engine that brings together a global reasoning community and keeps score for thousands of forecasters, delivering machine learning-optimized aggregate forecasts on topics of global importance. The Metaculus forecasting community is often inspired by altruistic causes, and Metaculus has a long history of partnering with nonprofit organizations, university researchers and companies to increase the positive impact of its forecasts.

Metaculus therefore poses questions about the occurrence of a variety of future events, on many timescales, to a community of participating forecasters — you!

What is forecasting?

Forecasting is a systematic practice of attempting to answer questions about future events. On Metaculus, we follow a few principles to elevate forecasting above simple guesswork:

First, questions are carefully specified so that everyone understands beforehand and afterward which kinds of outcomes are included in the resolution, and which are not. Forecasters then give precise probabilities that measure their uncertainty about the outcome.

Second, Metaculus aggregates the forecasts into a simple median (community) prediction, and an advanced Metaculus Prediction. The Community Prediction is simple to calculate: it finds the value for which half of predictors predict a higher value, and half predict lower. Surprisingly, the Community Prediction is often better than any individual predictor! This principle is known as the wisdom of the crowd, and has been demonstrated on Metaculus and by other researchers. Intuitively it makes sense, as each individual has separate information and biases which in general balance each other out (provided the whole group is not biased in the same way).

Third, we measure the relative skill of each forecaster, using their quantified forecasts. When we know the outcome of the question, the question is “resolved”, and forecasters receive their scores. By tracking these scores from many forecasts on different topics over a long period of time, they become an increasingly better metric of how good a given forecaster is. We use this data for our Metaculus Prediction, which gives greater weight to predictions by forecasters with better track records. These scores also provide aspiring forecasters with important feedback on how they did and where they can improve.

When is forecasting valuable?

Forecasting is uniquely valuable primarily in complex, multi-variable problems or in situations where a lack of data makes it difficult to predict using explicit or exact models.

In these and other scenarios, aggregated predictions of strong forecasters offer one of the best ways of predicting future events. In fact, work by the political scientist Philip Tetlock demonstrated that aggregated predictions were able to outperform professional intelligence analysts with access to classified information when forecasting various geopolitical outcomes.

Why should I be a forecaster?

Research has shown that great forecasters come from various backgrounds—and oftentimes from fields that have nothing to do with predicting the future. Like many mental capabilities, prediction is a talent that persists over time and is a skill that can be developed. Steady quantitative feedback and regular practice can greatly improve a forecaster's accuracy.

Some events — such as eclipse timing and well-polled elections, can often be predicted with high resolution, e.g. 99.9% likely or 3% likely. Others — such as the flip of a coin or a close horse-race — cannot be accurately predicted; but their odds still can be. Metaculus aims at both: to provide a central generation and aggregation point for predictions. With these in hand, we believe that individuals, groups, corporations, governments, and humanity as a whole will make better decisions.

As well as being worthwhile, Metaculus aims to be interesting and fun, while allowing participants to hone their prediction prowess and amass a track-record to prove it.

Who created Metaculus?

Metaculus originated with two researcher scientists, Anthony Aguirre and Greg Laughlin. Aguirre, a physicist, is a co-founder of The Foundational Questions Institute, which catalyzes breakthrough research in fundamental physics, and of The Future of Life Institute, which aims to increase the benefit and safety of disruptive technologies like AI. Laughlin, an astrophysicist, is an expert at predictions from the millisecond predictions relevant to high-frequency trading to the ultra-long-term stability of the solar system.

Is Metaculus a prediction market?

Sort of. Like a prediction market, Metaculus aims to aggregate many people's information, expertise, and predictive power into high-quality forecasts. However, prediction markets generally operate using real or virtual currency, which is used to buy and sell shares in "event occurrence." The idea is that people buy (or sell) shares if they think that the standing prices reflect too low (or high) a probability in that event. Metaculus, in contrast, directly solicits predicted probabilities from its users, then aggregates those probabilities. We believe that this sort of "prediction aggregator" has both advantages and disadvantages relative to a prediction market.

Are Metaculus Questions Polls?

No. Opinion polling can be a useful way to gauge the sentiment and changes in a group or culture, but there is often no single "right answer", as in a Gallup poll "How worried are you about the environment?". Polling may also be very helpful in predictions; consistent polling that a political candidate has 60% support of registered voters might mean that they're very likely to win the next election.

In contrast, Metaculus Questions should always be objective (like in Will Brent Crude Oil top $140/barrel before May 2022?), and forecasters are not asked for their preferences, but for their predictions, and over many predictions, they accrue a track record showing by how accurate they were. You can see Metaculus’ track record here. We also rank users according to their forecasting prowess. Additionally, a Community Prediction of 30% doesn't mean 30% of users predicted "Yes", and 70% said "No", instead, each user gives a probability between 0% and 100%, and we show the median of those forecasts.

Metaculus Questions

What sorts of questions are allowed, and what makes a good question?

Questions should focus on tangible, objective facts about the world which are well-defined and not a matter of opinion. “When will the United States collapse?” is a poor, ambiguous question; What will be the US' score in the Freedom in the World Report for 2050? is more clear and definite. They generally take the form Will (event) X happen by (date) Y? or When will (event) X occur? or What will the value or quantity of X be by (date) Y?

A good question will be unambiguously resolvable. A community reading the question terms should be able to agree, before and after the event has occured, whether the outcome satisfies the question’s terms.

Questions should also follow some obvious rules:

  1. Questions should respect privacy and not address the personal lives of non-public figures.
  2. Questions should not be directly potentially defamatory or generally in bad taste.
  3. Questions should never aim to predict mortality of individual people or even small groups. In cases of public interest (such as court appointees and political figures), the question should be phrased in other more directly relevant terms such as "when will X no longer serve on the court" or "will Y be unable to run for office on date X". When the topic is death (or longevity) itself questions should treat people in aggregate or hypothetically.
  4. More generally, questions should avoid being written in a way that incentivizes illegal or harmful acts — that is, hypothetically, if someone were motivated enough by a Metaculus Question to influence the real world and change the outcome of a question's resolution, those actions should not be inherently illegal or harmful.

Who creates the questions, and who decides which get posted?

Many questions are launched by Metaculus staff, but any logged-in user can propose a question. Proposed questions will be reviewed by a group of moderators appointed by Metaculus. Moderators will select the best questions submitted, and help to edit the question to be clear, well-sourced, and aligned with our writing style.

Metaculus hosts questions on many topics, but our primary focus areas are Science, Technology, Effective Altruism, Artificial Intelligence, Health, Geopolitics, and Far-Future Forecasting (10 years or more in the future).

Who can edit questions?

How can I get my own question posted?

  1. If you have a basic idea for a question but don’t have time/energy to work out the details, you’re welcome to submit it, discuss it in our question idea thread, or on our Discord channel.
  2. If you have a pretty fully-formed question, with at least a couple of linked references and fairly careful unambiguous resolution criteria, it’s likely that your question will be reviewed and launched quickly.
  3. Metaculus hosts questions on many topics, but our primary focus areas are Science, Technology, Effective Altruism, Artificial Intelligence, Health, Geopolitics, and Far-Future Forecasting (10 years or more in the future). Questions on other topics, especially that require a lot of moderator effort to get launched, will be given lower priority and may be deferred until a later time.
  4. We regard submitted questions as suggestions and take a free hand in editing them. If you’re worried about having your name on a question that is altered from what you submit, or would like to see the question before it’s launched, please note this in the question itself; questions are hidden from public view until they are given “upcoming” status, and can be posted anonymously upon request.

What can I do if a question I submitted has been pending for a long time?

We currently receive a large volume of question submissions, many of which are interesting and well-written. That said, we try to approve just enough questions that they each can get the attention they deserve from our forecasters. Metaculus prioritizes questions on Science, Technology, Effective Altruism, Artificial Intelligence, Health, Geopolitics, and Far-Future Forecasting (10 years or more in the future); if your question falls into one of these categories, or is otherwise very urgent or important, you can tag us with @moderators to get our attention.

What can I do if a question should be resolved but isn't?

If a question is still waiting for resolution, check to make sure there hasn’t been a comment from staff explaining the reason for the delay. If there hasn’t, you can tag @admins to alert the Metaculus team. Please do not use the @admins tag more than once per week regarding a single question or resolution.

What is a discussion question?

Discussion questions are spaces where discussions can happen on topics that don’t yet have (or may never have) quantified forecasts attached to them. They can be useful places for the community to have discussions when no other space is available, or for the Metaculus Team to communicate to the users (and vice-versa).

What is a private question?

Private questions are questions that are not visible to the broader community. They aren't subject to the normal review process, so you can create one and predict on it right away. You can resolve your own private questions at any time, but points for private predictions won't be added to your overall Metaculus score and they won't affect your ranking on the leaderboard.

You can use private questions for anything you want. Use them as practice to calibrate your predictions before playing for points, create a question series on a niche topic, or pose personal questions that only you can resolve. You can even invite other users to view and predict on your own questions!

What are the rules and guidelines for comments and discussions?

We have a full set of community etiquitte gudielines but in summary:

What do "credible source" and "by [date X]" and such phrases mean exactly?

To reduce ambiguity in an efficient way, here are some definitions that can be used in questions, with a meaning set by this FAQ:

  1. A "credible source" will be taken to be an online or in-print published story from a journalistic source, or information publicly posted on a the website of an organization by that organization making public information pertaining to that organization, or in another source where the preponderance of evidence suggests that the information is correct and that there is no significant controversy surrounding the information or its correctness. It will generally not include unsourced information found in blogs, facebook or twitter postings, or websites of individuals.
  2. The phrase "By [date X] will be taken to mean prior to the first moment at which [date X] would apply, in UTC. For example, "By 2010" will be taken to mean prior to midnight January 1, 2010; "By June 30" would mean prior to midnight (00:00:00) UTC June 30.

Question Resolution

What are the "open date", "close date" and "resolve date?"

Questions must contain an open date, a close date and a resolve date.

The close date must be at least one hour prior to the resolve date, but generally will be much earlier, depending upon the context. Metaculus differs from prediction markets in one respect: prediction markets can generally remain open even when the outcome is obvious without any adverse incentives to predict contrary to your true beliefs. On Metaculus, however, our scoring system is most fair and accurate when questions close while there is still reasonable uncertainty about the outcome.

Here are some guidelines:

Who decides the resolution to a question?

After the closing date, questions are eligible to be resolved. Binary questions can resolve positive, negative or ambiguous. Range questions can resolve to a specific value, an out-of-bounds value, or ambiguous. Only Metaculus Administrators can resolve questions. An ambiguous resolution generally implies that there was some inherent ambiguity in the question, that real-world events subverted one of the assumptions of the question, or that there is not a clear consensus as to what in fact occurred.

Do all questions get resolved?

Currently, all questions will be resolved.

When will a question be resolved?

Questions will be resolved when they have satisfied the criteria specified in the resolution section of the question (or conversely, when those criteria have conclusively failed to be met). Each question also has a “Resolution Date” listed in our system for purposes such as question sorting; however, this listed date is often nothing more than an approximation, and the actual date of resolution may not be known in advance.

For questions which ask when something will happen (such as When will the first humans land successfully on Mars?) forecasters are asked to predict the date/time when the criteria have been satisfied (though the question may be decided and points awarded at some later time, when the evidence is conclusive). Some questions predict general time intervals, such as “In which month will unemployment pass below 4%?”; when such a question has specified the date/time which will be used, those terms will be used. If these terms are not given, the default policy will be to resolve as the midpoint of that period (for example, if the January report is the first month of unemployment under 4%, the resolution date will default to January 15).

What happens if a question gets resolved in the real world prior to the close time?

When resolving a question, the Moderator has an option to change the effective closing time of a question, so that if the question is unambiguously resolved prior to the closing time, the closing time can be changed to a time prior to which the resolution is uncertain.

When a question closes early, the points awarded are only those accumulated up until the (new) closing time. This is necessary in order to keep scoring "proper" (i.e. maximally reward predicting the right probability) and prevent gaming of points, but it does mean that the overall points (positive or negative) may end up being less than expected.

What happens if a question's resolution criteria turn out to have been fulfilled prior to the opening time?

Our Moderators and question authors strive to be as clear and informed as possible on each question, but mistakes occasionally happen, and will be decided by our Admins' best judgement. For a hypothetical question like Will a nuclear detonation occur in a Japanese City by 2030? it can be understood by common sense that we are asking about the next detonation after the detonations in 1945. In other questions like Will Facebook implement a feature to explain news feed recommendations before 2026?, we are asking about the first occurence of this event. Since this event occured before the question opened and this was not known to the question author, the question resolved ambiguously.

What happens if a resolution source is no longer available?

There are times when the intent of a question is to specifically track the actions or statements of specific organizations or people (such as, "how many Electoral Votes will the Democrat win in the 2020 US Presidential Election according to the Electoral College"); at other times, we are interested only in the actual truth, and we accept a resolution source as being an acceptable approximation (such as, "how many COVID-19 deaths will there be in the US in 2021 according to the CDC?"). That said, in many cases it is not clear which is intended.

Ideally, every question would be written with maximally clear language, but some ambiguities are inevitable. Unless specifically indicated otherwise, if a resolution source is judged by Metaculus Admins to be defunct, obsolete, or inadequate, Admins will make a best effort to replace it with a functional equivalent. Questions can over-rule this policy with language such as "If [this source] is no longer available, the question will resolve Ambiguously" or "This question tracks publications by [this source], regardless of publications by other sources."

Predictions

How do I make a prediction? Can I change it later?

You make a prediction simply by sliding the slider on the question's page to the probability you believe most captures the likelihood that the event will occur.

You can revise your prediction at any time up until the question closes, and you are encouraged to do so: as new information comes to light, it is beneficial to take it into account.

You're also encouraged to predict early, however, and you are awarded bonus points for being among the earliest predictors.

How is the Community Prediction calculated?

The Community Prediction is the median (that is, middle value) of recent player predictions. It's designed to respond to big changes in player opinion while still being fairly insensitive to outliers.

Here's the mathematical detail.

Users can hide the Community Prediction from view from within their settings. This requires that the user be at least Level 2, or that they purchase this power using tachyons.

What is the Metaculus Prediction?

The Metaculus Prediction is the Metaculus system's best estimate of how a question will resolve. It's based on predictions from community members, but unlike the Community Prediction, it's not a simple average or median. Instead, the Metaculus Prediction uses a sophisticated model to calibrate and weight each user, ideally resulting in a prediction that's better than the best of the community.

For questions that resolved in 2021, the Metaculus Prediction has a Brier score of 0.107. Lower Brier scores indicate greater accuracy, with the MP slightly lower than the Community Prediction's Brier score of 0.108. you can see some of the fine details on our track record page.

What Are Public Figure Predictions?

Public Figure Predictions pages are dedicated to collecting and preserving important predictions made by prominent public figures and putting them into conversation with Metaculus community forecasts. Each figure’s page features a list of predictions they made along with the source that recorded the prediction, the date the prediction was made, and related Metaculus questions. Public predictions are transparently presented alongside community forecasts in a manner that is inspectable and understandable by all, providing public accountability and additional context for the linked Metaculus questions. 

A Public Figure is someone with a certain social position within a particular sphere of influence, such as a politician, media personality, scientist, journalist, economist, academic, or business leader. 

What qualifies as a prediction?

A prediction is a claim or a statement about what someone thinks will happen in the future, where the thing predicted has some amount of uncertainty associated with it. 

A Public Figure Prediction is a prediction made by the public figure themselves and not by figures who might represent them, such as employees, campaign managers, or spokespeople.

Who can submit Public Figure Predictions?

When predictions are made by public figures such as elected politicians, public health officials, economists, journalists, and business leaders, they become candidates for inclusion in the Public Figure Prediction system. All Metaculus community members at Level 2 or above can help by linking public figure predictions that are publicly accessible and from reputable sources.

How can I submit a Public Figure Prediction?

From a Public Figure's page, click Report Prediction and then provide

  1. A direct quotation from the prediction news source
  2. The name of the news source
  3. A link to the news source
  4. The prediction date
  5. At least one related Metaculus question

If the Public Figure does not yet have a dedicated page, you can request that one be created by commenting on the Public Figures Predictions discussion post with the five elements above. Once three public figure predictions for that public figure are submitted via comments and approved by moderators, a new page will be created for them.

What makes a good quotation highlight?

The aim of the highlight is to present the essence of the Public Figure's prediction. For the given example quotation:

In October, Elon Musk, the CEO and founder of SpaceX, proclaimed that in 2024 humans would set foot on Mars.” 

The highlighted portion “proclaimed that in 2024 humans would set foot on Mars” emphasizes the prediction being made while the rest of the quotation provides further context. To highlight within the quotation, use two * characters before and after the portion you’d like to highlight. Note that you should only include text from the linked source and in the order presented there. Some text can be elided and replaced with an ellipsis character: … but this must not change the underlying intended meaning of the quote. 

What are the criteria for selecting linked Metaculus questions related to the Public Figure Prediction?

Depending on the level of specificity and clarity of the Public Figure Prediction, a linked Metaculus question might resolve according to the exact same criteria as the prediction. For example, Joe Biden expressed that he plans to run for reelection. This Metaculus question asks directly whether he will run.  

Linked questions are not required, however, to directly correspond to the public figure’s prediction, and this question on whether Biden will be the Democratic nominee in 2024 is clearly relevant to public figure claim, even as it’s further away from the claim than asking whether Biden will run. Relevant linked questions shed light on, create additional context for, or provide potential evidence for or against the public figure’s claim. Note that a question being closed or resolved does not disqualify it from being linked to the prediction.

On the other hand, this question about whether the IRS designates crypto miners as ‘brokers’ by 2025 follows from Biden’s Infrastructure Investment and Jobs Act, but beyond the Biden connection, it fails to satisfy the above criteria for a relevant linked question.

Which sources are acceptable?

News sources that have authority and are known to be accurate are acceptable. If a number of news sources report the same prediction, but the prediction originated from a single source, using the original source is preferred. Twitter accounts or personal blogs are acceptable if they are owned by the public figure themselves

Who decides what happens next?

Moderators will review and approve your request or provide feedback.

What happens if a public figure updates their prediction?

On the page of the prediction, comment the update with the source and tag a moderator. The moderator will review and perform the update if necessary.

I am the Public Figure who made the prediction. How can I claim this page?

Please email us at support at metaculus.com.

Scoring

What is a Brier score?

The Brier score is a commonly-used scoring rule (sometimes also called "quadratic scoring") that compares a set of predictions to actual outcomes. For a single forecast of probability \(p\), it is computed as \(S=(p-f)^2\), where \(f=1\) if the event occurred, and \(f=0\) if not. If you forecast 100% and an event occurred, your Brier score would be 0. If you forecast 100% and it did not occur, your score would be 1. If you were to guess 50% for every binary question, your mean Brier score would be 0.25.

What is a log score?

The log score is another common scoring rule. Outside tournaments, Metaculus uses a variant of the log score. For a single binary forecast of probability \(p\), the log score is computed as \(S=(\log_2 p)+1\) if the event occurred, and \(S=(\log_2 (1-p))+1\) if not. The scaling is chosen so that higher scores are better, and a maximally-uncertain prediction (p=0.5) gives S=0. For continuous questions, the score is computed as \(S=\log_2 p\), where p is the value of the predicted probability density at the resolved value (as can be read off from the plot on the question). Fun fact: a variant of the log score is used to calculate Metaculus points and tournament scores.

How are Metaculus Points calculated?

The points you receive depend upon your prediction, what actually happens, and what the rest of the community predicts. By sliding the slider, you can see how many points you will get if the question were resolved as 'yes' or 'no' right now. There are five key things you need to know about the points:

  1. Your expected points are maximized if you provide your true credence. For example, if the question was whether a fair coin would come up heads, then you would get most points by predicting 50% each time. You should always predict the probability you believe to best reflect the true likelihood of the event's occurrence.
  2. Points are awarded both for being right and for being more right than the community.
  3. Since your points are partially based on other player's predictions, the points "on the line" will change over time.
  4. The points you are awarded are time averaged over the time during which the question is open; you receive no points while a question is open but before you make a prediction, and the points you earn depend upon your predictions' accuracy and when they are made. This means both that you should make your first prediction early, so as to earn points over more of the question's lifetime, and also that you should update your prediction anytime new information comes to light that alters your best estimate of the probability.

Note that until 2022-26-4, a user's final forecast was awarded a 50% point bonus on questions that closed before they resolved. Ultimately it was determined that the drawbacks outweighed the benefits, and the bonus was discontinued. For more details, see this discussion post.

For further elaboration and discussion of how Metaculus scores forecasts, see this post written by one of Metaculus's founders.

For those who are interested and have a stomach for more mathematical detail, the technical details of the points calculation are as follows (click to reveal).

Your score \(S(T;f)\) at any given time \(T\) is the sum of an "absolute" component and a "relative" component: \[ S(T;f) = a(N) \times L(p;f) + b(N) \times B(p;f),\] where \(N\) is the number of predictors on the question. If we define \(f=1\) for a positive resolution of the question and \(f=0\) for a negative resolution, then \(L(p;f)=\log_2(p/0.5)\) for \(f=1\) and \(L(p;f)=\log_2((1-p)/0.5)\) for \(f=0\). The normalizations \(a(N) = 30+10\,\log_2(1+N/30)\) and \(b(N) = 20\,\log_2(1+N/30)\) depend on \(N\) only. The "betting score" \(-2 < B(p;f) < 2\) represents a bet placed against every other predictor. This is described under "constant pool" scoring on the Metaculus scoring demo (but with a modification that for computational efficiency, the distribution of other player predictions is represented by a fit to a beta distribution rather than the actual predictions.) The \(B, N,\) and \(p\) can all depend on \(T\) and contribute to the time-dependence of \(S(T)\), which is plotted in "score history." The final score given to the user upon question resolution is based on the time integral over \(S(T)\): \[ S= {1\over t_c-t_o}\int_{t_o}^{t_c} dT\,S(T) + \frac{1}{2}S(t_c), \] where \(t_o\) and \(t_c\) are the opening and closing times. (Note that \(S(T) = 0\) after the opening time but prior to your first prediction, and is also zero after question resolution but before question close, in the case when a question resolves early.) The current value of this integral is shown in the score history plot as the "average points."

How do predictions and points work for numerical questions?

Whereas binary questions resolve as either 'yes' or 'no', resolutions for numerical questions lie on a continuum of values. Therefore, when you make a prediction, you need to specify a probability for each possible outcome (that is, assign a probability density function.) There are an infinite number of such functions, but to make life a little bit easier we restrict predictions to single logistic distributions. You can adjust the center and width of your predictions using the sliders on the question pages.

Here are the key things you need to know, with more details below.

  1. You should put the center of your distribution at what you think is the most likely value, then adjust the width of the distribution so that you attribute better than even odds to the true number falling into your range.
  2. Making your distribution wider or narrower reflects your confidence in the central value you've specified, and decides the stakes: a narrower distribution give more points if your central value is right, but more losses if it's very wrong.
  3. As for binary questions, the scoring awards points both for being right and for being more right than the community, the points "on the line" will change with time, and the score you are awarded is time averaged over the time for which the question is open.
  4. Some numerical questions restrict the possible resolutions to lie within a certain range. If the resolution falls outside of that range, then the question resolves as ambiguous and no once receives points. Other questions allow for open-ended ranges, and you can assign high probability to an out-of-bounds resolution by moving your distribution to the edge of the range.

When a numerical prediction resolves, players are scored using a log scoring rule. The more probable you thought the outcome would be, the more points you'll get. Your prediction is compared to both a uniform distribution (where all outcomes are treated as equally likely) and the community's prediction. If you always predict that the resolved outcome is more likely than both the uniform prediction and the Community Prediction then you're guaranteed to win points. Just like the binary scoring rule, your final score is averaged over the lifetime of the question.

Every numeric question has a range of possible outcomes set by the question creator. The outcomes can be displayed on either a linear or logarithmic scale. If logarithmic, predictions will technically be log-logistic distributions, although the log scale will make them appear to have the same shape as regular logistic distributions. Let \(x\) be the resolved outcome and \(P_p(x)\) be the player's predicted probability (density) of that outcome. Then the player's score is given by \[ S(x) = A(N) \log\left(\frac{P_p(x)}{P_u}\right) + B(N) \log\left(\frac{P_p(x)}{P_c(x)}\right), \] where \(P_u\) is the probability density for a uniform distribution, \(P_c(x)\) is the logistic distribution which best fits all other players' predictions, and \(N\) is the number of other players. Both the player distribution and the community distribution are combined with a uniform distribution such that \(P_p(x)/P_u > 0.02\) always. This prevents the player from catastrophic point losses for erroneous over-confidence.

For questions that restrict the range of possible outcomes, the distributions are truncated to the restricted range and renormalized such that \(\int P(x)dx = 1\). For questions with open-ended ranges, the baseline “uniform” distribution contains a 15% probability of the resolution occurring outside of each open boundary. The exact value of an out-of-bounds resolution does not matter: players are scored only on the total probability that they assigned to the out-of-bounds possibility.

The functions \(A(N)\) and \(B(N)\) determine the overall point scaling,

The player's prediction, the community's prediction, and the number of other players can all change with time, so the scoring function is time-dependent as well. The final points awarded are the time-average of over the lifetime of the question, plus 50% of the final value of at question close.

Why did I only get a few points when I was right?

The Metaculus points system is designed to be a proper scoring rule. This means that your best strategy is to predict your true belief about the probability, or probability distribution of an event.

One somewhat counter-intuitive aspect of the scoring rule is that points will be truncated if a question resolves before its stated close time. This truncation is necessary in order to keep the scoring rule proper. Without the truncation, predictors would be incentivised to predict very high probabilities early on in a question, even if the true probability of the question resolving were low.

An intuitive way of understanding this is to think of each day (or in fact second) as being a separate “question” which generates its own score, where your prediction is whatever it was the last time you updated. The score over all time is therefore equal to the sum of the scores over each “part” of the question, and if each part is individually proper, then so will be the sum. The reason for truncation is now obvious, those “questions” which fell after the question resolved, score zero. Not truncating would mean weighing some early “questions” higher, breaking the properness.

Click below to see a worked out example.

This example uses the log score for ease of calculation, but similar logic holds for the Brier score, and for Metaculus points.

Bob wants to predict if he will be fired this year. He has a work review in one week, and there is a \(10\%\) chance he will fail it and be fired right after. If he passes the work review, there is still a \(5\%\) chance he will be fired at the end of the year. A proper scoring rule should mean that the best strategy on this question is to predict \(p = (0.1 + 0.9 \times 0.05) = 14.5\%\) for the first week, and then \(5\%\) thereafter (if he passed the review).

Without truncation (and assuming 52 weeks in a year), this strategy gives an expected log score of \(\ln(0.145) \simeq -1.93\) if he fails the review, and \(0.95 \left ( \frac{1}{52} \ln(0.855) + \frac{51}{52} \ln(0.95) \right ) + 0.05 \left ( \frac{1}{52} \ln(0.145) + \frac{51}{52} \ln(0.05) \right ) \simeq -0.199\) if he passes it, for a total expected score of \(0.1 \times (-1.92) + 0.9 \times (-0.199) \simeq -0.373\) .

But a strategy of predicting \(99\%\) for the first week, then \(5\%\) afterwards, scores \(0.1 \ln(0.99) + 0.9 \left ( 0.95 \left ( \frac{1}{52} \ln(0.01) + \frac{51}{52} \ln(0.95) \right ) + 0.05 \left ( \frac{1}{52} \ln(0.99) + \frac{51}{52} \ln(0.05) \right ) \right ) \simeq -0.252\), which is higher. So without truncation the log score is not a proper scoring rule!

On the other hand, if we truncate the score in case of early resolution, the expected score for the \(14.5\%/5\%\) strategy is now \(0.1 \frac{1}{52} \ln(0.145) + 0.9 \left ( 0.95 \left ( \frac{1}{52} \ln(0.855) + \frac{51}{52} \ln(0.95) \right ) + 0.05 \left ( \frac{1}{52} \ln(0.145) + \frac{51}{52} \ln(0.05) \right ) \right ) \simeq -0.183\), while the expected score for the \(99\%/5\%\) strategy is now \(0.1 \frac{1}{52} \ln(0.99) + 0.9 \left ( 0.95 \left ( \frac{1}{52} \ln(0.01) + \frac{51}{52} \ln(0.95) \right ) + 0.05 \left ( \frac{1}{52} \ln(0.99) + \frac{51}{52} \ln(0.05) \right ) \right ) \simeq -0.251\), which is lower, so our scoring is proper again!

Tournament Scoring

What is a relative log score?

To measure the accuracy of your forecast probability \(p\) relative to the community forecast probability \(p_c\), we define your relative log score for a binary question as \( \ln \frac{p}{p_c} \) if the event occurred and \( \ln \frac{1 - p}{1 - p_c} \) if it did not occur. If your forecast is the same as the community's, then you will always get a relative log score of \( \ln 1 = 0 \). If you forecast 20%, the community forecast 10%, and the event occurred then your relative log score is \( \ln \frac{0.2}{0.1} \simeq +0.693 \). If, instead, you forecast 10% and the community forecast 20% for an event that occurred, then your relative log score is \( \ln \frac{0.1}{0.2} \simeq -0.693 \).

For continuous questions, \(p\) is the density of your forecast probability distribution at the resolution value and \(p_c\) is the density of the community probability distribution at the resolution value. For an example, see the GDP forecast in our tournament scoring post.

What is my tournament question score?

Your tournament question score is a time average of your relative log score over the scheduled duration of a question. For times when you are not actively forecasting on a question, either because you didn’t join when the question opened or because you withdrew from the question, you are imputed the community forecast, i.e. your relative log score when you are not active is \( \ln 1 = 0 \).

What is my question coverage?

Your question coverage is the percentage of the relevant period (see Hidden Period and Coverage Weight below) in which you have an active forecast. If you have an active forecast during the entire duration of a question, your coverage is 100%. If you don’t forecast a question at all your coverage is 0%. For most tournaments, only your participation during the hidden period is relevant for determining your question coverage.

What is the hidden period?

For most tournament questions, the community prediction is hidden at the start of a question. This is done to prevent forecasters from simply copying the community, and accordingly rewards forecasting skill. The hidden period is defined as a proportion of the question's lifetime. If the question will be open 5 weeks and the hidden period is 20%, then the community prediction will stay hidden the first week.

What is the coverage weight?

The coverage weight is a question parameter that determines how coverage is calculated. When coverage weight is 100% then coverage is entirely determined by participation during the hidden period. This is the most common setting. However, when coverage weight is 50% then coverage is determined half by participation during the hidden period and half by participation when the community median is visible.

How is my tournament score calculated?

Your tournament score is the sum of your tournament question scores in a tournament. You can see how your tournament score is calculated on your personal scoreboard for a tournament.

How is my tournament coverage calculated?

Your tournament coverage is the average of your question coverage values for all the questions in a tournament. You can see how your tournament coverage is calculated on your personal scoreboard for a tournament.

How is my tournament take calculated?

Your tournament take determines how much of the prize pool you win compared to other forecasters. If your take is twice as big as another forecaster’s take, then you will win twice the prize. The tournament take for a forecaster is their tournament coverage times the exponential of their tournament score.

Metaculus Journal

What is the Metaculus Journal?

The Metaculus Journal publishes longform, educational essays on critical topics like emerging science and technology, global health, biosecurity, economics and econometrics, environmental science, and geopolitics—all fortified with testable, quantified forecasts.

If you would like to write for the Metaculus Journal, email christian@metaculus.com with a resume or CV, a writing sample, and two story pitches.

What is a fortified essay?

In November 2021 Metaculus introduced a new project - Fortified Essays. A Fortified Essay is an essay that is “fortified” by its inclusion of quantified forecasts which are justified in the essay. The goal of Fortified Essays is to leverage and demonstrate the knowledge and intellectual labor that went into answering forecasting questions while also putting the forecasts into a larger context.

Metaculus plans to run Fortified Essay Contests regularly as part of some tournaments. This additional context deriving from essays is necessary, because a quantified forecast in isolation may not provide the information required to drive decision-making by stakeholders. In Fortified Essays, writers can explain the reasoning behind their predictions, discuss the factors driving the predicted outcomes, explore the implications of these outcomes, and can offer their own recommendations. By placing forecasts into this larger context, these essays are better able to help stakeholders deeply understand the relevant forecasts and how much weight to place on them. The best essays will be shared with a vibrant and global effective altruism community of thousands of individuals and dozens of organizations.

Forecasting Causes

Forecasting Causes makes it easy for organic communities of interest to form around specific altruistic causes, and to connect the dots between the Metaculus forecasting community and nonprofits that are deeply engaged in doing world-changing work. It’s as simple as making forecasts the way we always have, with added features that bring focus to specific areas of need and generate prizes to motivate quality predictions where it matters.

What are Forecasting Causes?

Forecasting Causes is a framework that Metaculus has created in order to more effectively partner with and serve altruistic movements and the nonprofits that work within. Tournaments and forums provide community spaces for people who want to boost good forecasts for a Cause, on the questions most likely to impact future decision-making. By supporting causes financially, community members and nonprofits alike can encourage good forecasting, resulting in effective change.

Why is Metaculus doing this?

Forecasting Causes is a continuation of work Metaculus has done for years. The Metaculus community is often inspired by altruistic causes, and Metaculus has a long history of partnering with nonprofit organizations and university researchers. By supporting with technology what has to-date been an informal process, we hope to increase the positive impact of our forecasts.

How do Forecasting Causes work?

Forecasting Cause pages serve as a home for the community interested in a particular cause. Each cause has dedicated Discussion Forums and Tournaments. Also on these pages, you’ll be able to see and learn more about our nonprofit partner organizations. Community members can pledge to support a cause through a monthly subscription, which will be used to fund tournaments. Nonprofits can make lump sum donations in support of a cause.

How can I get involved?

If you’d like to boost good forecasts in a particular Forecasting Cause, you can participate in a number of valuable ways:

If you’re part of a nonprofit looking to use the power of forecasting to further your cause, reach out to us at hello (at) metaculus (dot) com.

What are Forecasting Cause Supporters?

Forecasting Cause Supporters are people who choose to financially support a particular Forecasting Cause on Metaculus. Funds contributed by Supporters increase the cause’s current tournament prize pool and also support operations for the cause and tournament.

I'm interested in creating a tournament

A forecasting tournament is a competition across one or multiple rounds of questions. Forecasters make their predictions on these questions, and once the questions are resolved, the forecasters are scored and ranked based on their accuracy. The top ranked forecasters can then receive payouts from a prize pool set aside for the tournament (in addition to other rewards like Metaculus hoodies), as well as the recognition that comes from winning the tournament.

Running a tournament allows Metaculus to produce a larger number of forecasts for a larger volume of questions more quickly. If your organization would be interested in running a forecasting tournament on a given topic, you can contact us at hello@metaculus.com or use our feedback form on the footer of the page.

Miscellany

What are tachyons?

A tachyon is a particle that can go back in time. On Metaculus, tachyons power users' special retrocausal abilities and allow for the purchase of new abilities—such as unmaking predictions, or revealing the Metaculus Prediction before a question closes. Every week you can collect 10 tachyons by logging in, up to a maximum of 50. You can also earn tachyons as a bonus for reaching achievements, such as “Evangelist” or “Beating the Crowd.” You’ll receive 5, 10, and 50 tachyon bonuses as you reach the 1st, 2nd, and 3rd ranks of an achievement.

What do tachyonic powers cost and when are they activated?

Powers can be unlocked by attaining the requisite level, or you can pay a premium to get access to a power early. Unlocking a power costs 10 times the sum of the levels between your current level and the unlock requirement level. So if you’re level 4 and the unlock level is 6, the unlock cost would be 10*(5+6) or 110 tachyons.

The current powers, their levels, and their tachyon prices are:

Tachyons costs are subject to change in the future.

What achievements are available?

Each achievement has three ranks. Below are the criteria for moving up through each achievement’s ranks.

Does Metaculus have an API?

The Metaculus API can be found here: https://www.metaculus.com/api2/

How do I change my username?

You can change your name for free within the first three days of registering. After that it will cost you 15 tachyons. Note that after you change your name, you’ll be unable to change it again for 180 days.

I’m registered. Why can’t I comment on a question?

In an effort to reduce spam, new users must wait 12 hours after signup before commenting is unlocked.

Understanding account suspensions.

Metaculus may—though this thankfully occurs very rarely—issue the temporary suspensions of an account. This occurs when a user has acted in a way that we consider inappropriate, such as when our terms of use are violated. At this point, the user will be received a notice about the suspension, and be made aware that continuing this behaviour is unacceptable. Temporary suspensions serve as a warning to users that they are few infractions away from receiving a permanent ban on their account.

Why can I see the Community Prediction on some questions, the Metaculus Prediction on others, and no prediction on some others?

When question first opens, nobody can see the Community Prediction for a while, to avoid giving inordinate weight to the very first predictions, which may "ground" or bias later ones. Once the Community Prediction is visible, the Metaculus Prediction is hidden until the question closes, though it may be peeked at using tachyons.

NewsMatch displays a selection of articles relevant to the current Metaculus question. These serve as an additional resource for forecasters as they discuss and predict on the question. Each article is listed with its source and its publication date. Clicking an article title navigates to the article itself. Clicking the ‘rate’ button allows you to indicate whether the article was helpful or not. Your input improves the accuracy and the usefulness of the model that matches articles to Metaculus questions.

The article matching model is supported by Improve the News, a news aggregator developed by a group of researchers at MIT. Designed to give readers more control over their news consumption, Improve the News helps readers stay informed while encountering a wider variety of viewpoints.

Articles in ITN's database are matched with relevant Metaculus questions by a transformer-based machine learning model trained to map semantically similar passages to regions in "embedding space." And the embeddings themselves are generated using MPNet. Once a match is made, it must still be manually approved before it can appear alongside a forecast question.

Can I get my own Metaculus?

Maybe! Metaculus has a domain system, where each domain (like "example.metaculus.com") has a subset of questions and users that are assigned to it. Each question has a set of domains it is posted on, and each user has a set of domains they are a member of. Thus a domain is a flexible way of setting a particular set of questions that are private to a set of users, while allowing some questions in the domain to be posted also to metaculus.com. Domains are a product that Metaculus can provide with various levels of support for a fee; please be in touch for more details.

How can I help spread the word about Metaculus?

Metaculus will get more fun and more interesting to the extent that it grows to include more and more predictors, so we encourage participants to spread the word to people who they think may enjoy predicting, or just be interested in how the questions develop. Some of the most useful mechanisms are:

  1. Post particular questions you like to Twitter, Facebook and Reddit, using the "share" button on each page, which sets up a default tweet/post that you can edit.
  2. Follow us on Twitter, then retweet Metaculus tweets to your followers.
  3. Follow our Facebook page, and share posts you like.
  4. Contact us for other ideas.