Forecast methodology
How the probability works
Every forecast starts with the rumour's source and claim, then adjusts as supporting or conflicting evidence arrives. The goal is a clear confidence signal, not false certainty.
Source quality
Every piece of evidence has a source-strength rating. Stronger, more authoritative sources carry more confidence, while early community and speculative signals are treated cautiously.
✓ Official: Information published directly by the artist, festival, promoter, venue or another authoritative first-party source.
★★★★★ Direct Statement: Direct comments or highly authoritative first-hand evidence.
★★★★☆ Trusted Media: Reporting from established media or other strong professional sources.
★★★☆☆ Insider & Tour Intelligence: Credible industry, touring or specialist intelligence that is not officially confirmed.
★★☆☆☆ Emerging & Community Signal: Early reporting, community intelligence or less established sourcing that may still be useful.
★☆☆☆☆ General Speculation: Unverified rumours, anonymous leaks or speculative community signals. Useful as early intelligence, but treated cautiously.
Evidence strength
Claim strength describes what the source is claiming. A direct confirmation is stronger than a report that talks are happening, while a rumour or piece of speculation adds a smaller signal. For example, an eFestivals Strong Rumour carries more weight than a standard Rumour, but both remain Emerging & Community Signals until stronger independent sourcing emerges.
Impact
Impact measures how strongly a specific piece of evidence should influence a rumour. It is separate from source strength and claim strength, so an Emerging & Community Signal can be useful without being treated like direct confirmation.
It considers:
- How direct the evidence is
- How reliable the source is
- Whether it supports, weakens, or only provides context
- How relevant it is to Glastonbury
Impact is shown as:
The probability engine uses a more detailed internal impact score behind the scenes.
Positive, neutral and negative evidence
Positive evidence raises the forecast. Neutral evidence is useful context but does not move the number. Negative evidence, such as a denial or scheduling clash, lowers it.
Corroboration
Several independent reports can strengthen a rumour. Each extra source helps a little less than the one before it, so repeated coverage does not overwhelm the forecast.
Source caps
The forecast is limited by the quality of its best available source. A collection of weak signals cannot produce the same confidence as one genuinely trusted report.
Official confirmation
A 100% probability means there is official confirmation, or an equivalent confirmation from a source trusted enough to settle the question.