---
name: forecasting
description: "Produce forecasts that can be challenged and learned from later. Use an outside view, explicit uncertainty, pre-outcome assumptions and a durable forecast record instead of one-point certainty and reconstructed hindsight."
---

# Forecasting

Produce forecasts that can be challenged and learned from later. Use an outside view, explicit uncertainty, pre-outcome assumptions and a durable forecast record instead of one-point certainty and reconstructed hindsight.

## When to use

- A project deadline or outcome estimate is built mostly from an inside plan.
- A recent vivid case is driving the probability estimate.
- A current feeling or preference is being projected far into the future.
- A team wants to learn from forecasts rather than remember them selectively.

## Workflow

1. Define exactly what is being forecast, the horizon and the observable resolution condition.
2. Start with comparable completed cases or another defensible outside-view reference when available.
3. Give a range or probability with the factors that would move the outcome toward either end.
4. Record assumptions, data date and major unknowns before the outcome is known.
5. Identify one or more signals that should update the forecast before the final outcome.
6. After resolution, compare the outcome with the original record rather than reconstructed memory, and separate forecast quality from luck.

## Required output

- Forecast question and resolution rule
- Outside-view reference
- Estimate / range and uncertainty
- Assumptions and update signals
- Timestamped forecast record
- Post-resolution review when applicable

## Evidence and safety boundaries

- Do not hide weak evidence behind precise decimals.
- Do not rewrite the original forecast after the outcome.
- Do not treat one correct forecast as proof of a generally good process.
- Keep reference-class mismatch visible.
## Evidence-linked lenses

Use these as candidate lenses, not diagnoses:

- [Planning Fallacy](https://cognitive-biases.github.io/biases/egocentric-bias-planning-fallacy/) — The planning fallacy is a well-documented tendency for people to predict their own task completion times too optimistically. The effect has been observed across different kinds of tasks, but it is not a rule that every plan will run late. Project overruns can also come from changing scope, dependencies, incentives, poor data, deliberate underestimation, or genuinely unusual events, so a late project should not automatically be diagnosed as a planning fallacy.
- [Anchoring Effect](https://cognitive-biases.github.io/biases/cognitive-bias-anchoring-effect/) — Anchoring is a well-supported effect in which an initial numerical value can pull a later estimate toward it. A 2026 meta-analysis covering 2,601 effect sizes found a large overall effect, but also substantial variation across studies. The effect should not be treated as a rule that every number changes every judgment: incidental anchors, anchors from a different dimension, clearly random values, incentives, and some debiasing conditions were associated with smaller or null effects.
- [Availability Heuristic](https://cognitive-biases.github.io/biases/heuristic-bias-availability-bias/) — Availability is a judgment heuristic: people can use how easily examples or scenarios come to mind when estimating frequency or probability. That shortcut is not automatically an error because memorable or accessible examples can correlate with real frequency. Bias appears when accessibility is driven by factors that are not diagnostic of the quantity being judged.
- [Hindsight Bias](https://cognitive-biases.github.io/biases/cognitive-bias-hindsight-bias/) — Knowing an outcome can make the outcome look more predictable in retrospect. The effect has been studied for decades and across many settings, but it does not mean that every confident explanation after an event is biased.

## References

- [Decision skill](https://cognitive-biases.github.io/skills/forecasting/)
- [Project estimation context](https://cognitive-biases.github.io/contexts/project-estimation-delivery/)

## Portability

This is an instruction-only Agent Skill. It requires no secrets, no executable scripts and no network access to run. If source-access tools are available, use the linked Cognitive Biases material to preserve review state and uncertainty.

Licence: CC BY-NC-SA 4.0. Commercial reuse requires prior written permission.