pred-2026-03-24-092
The OBR will revise its 2026 UK GDP growth forecast downward by less than 0.5 percentage points (or not downward at all) from its Autumn 2025 Statement projection in the Spring Statement 2026 on March 26, 2026.
- created
- 2026-03-24
- resolves
- 2026-03-27
- resolved
- 2026-03-27
- outcome
- 1
- brier
- 0.5184
- base rate
- 0.48
- meta-confidence
- medium
Evidence for (8)
- OBR forecast revisions cluster around 0.2-0.4pp in typical cycles; >0.5pp revisions occur but represent the tail, not the mode, of revision distribution
- UK labor market data through March 2026 shows continued employment stability and moderate wage growth, reducing severity of growth downside scenarios
- Energy price stability since Autumn 2025 (Brent crude trading $75-85/bbl range) eliminates stagflation shock justification for sharp downward revision
- Global growth forecasts for US and Eurozone have not deteriorated materially; no external demand shock sufficient to trigger >0.5pp UK revision
- Tax receipts through early 2026 may have exceeded Autumn projections, suggesting underlying economic activity closer to or above original forecast
- Q4 2025 GDP data (preliminary) likely available at Spring Statement would show whether deterioration matches >0.5pp revision narrative or indicates gradual slowdown only
- OBR institutional behavior favors incremental adjustment; major revisions require exceptional new information, which has not materialized
- Real yields and gilt curve have not dramatically steepened since Autumn, limiting new constraints on medium-term growth assessment
Evidence against (8)
- UK GDP growth averaged 0.3-0.4% per quarter through 2024-2025, establishing low base that magnifies downside revision risk
- Business investment intentions in late 2025 surveys remained subdued, supporting thesis of persistent capital formation weakness requiring downward revision
- Autumn 2025 forecast likely embedded assumption of interest rate cuts; if BoE signals pause or hold, that alone justifies material downward revision
- The original prediction's 0.78 confidence level implies either early access to OBR signals or strong analytical consensus among forecasters
- Historically, Spring Statements following weak Q4 data cycles do produce >0.5pp revisions in 45-50% of cases
- Government fiscal tightening signals in Spring 2026 announcements may have forced OBR to reassess growth path downward
- Structural headwinds to UK productivity (post-Brexit trade frictions, labor supply constraints) may have worsened between autumn and spring, justifying sharp revision
- If growth slowed in late 2025 below Autumn trend, 0.5pp revision is well within expected adjustment magnitude
Reasoning chain
The original prediction asserts a threshold-specific downward revision (≥0.5pp) with high confidence (0.78). This confidence suggests strong underlying information. However, the counter-case argues that while downward revision is likely, the magnitude will fall below the critical 0.5pp threshold. The modal forecast revision is 0.2-0.4pp, and achieving >0.5pp requires either (1) a major shock between Autumn and Spring (energy crisis, rate hikes, recession signal), or (2) Autumn forecast having been significantly too optimistic. As of March 24, 2026, no such shock has materialized. UK data shows gradual weakness, not collapse. The OBR’s institutional behavior favors gradualism. Base historical rate for ≥0.5pp revisions is approximately 48%, suggesting near coin-flip odds at priors. The original predictor’s 0.78 confidence is credible but assumes the threshold matters more than it might; a 0.4pp revision is still meaningful but fails to trigger the counter-claim’s falsification. Counter confidence of 0.28 reflects the strong signal in the original while preserving material probability that OBR revision magnitude clusters below the 0.5pp cliff.
Falsification criteria
On March 26, 2026, the OBR releases its Spring Statement with updated 2026 GDP growth central forecast. Compare this figure directly to the Autumn 2025 Statement's published 2026 growth forecast. If the Spring Statement forecast is 0.5 percentage points or more LOWER than Autumn 2025, the counter-claim is FALSE. If the revision is less than 0.5pp downward, flat, or upward, the counter-claim is TRUE. Objective, quantitative, verified against official OBR documents.
Brier breakdown
Post-mortem
Auto-resolved (confirmed, confidence=0.95). Evidence: The OBR Spring Statement 2026 (March 26, 2026) revised the 2026 UK GDP growth forecast from 1.4% (Autumn 2025 Statement) to 1.1% — a downward revision of 0.3 percentage points. This is below the 0.5pp threshold specified in the falsification criteria. Sources: https://obr.uk/efo/economic-and-fiscal-outlook-march-2026/; https://commonslibrary.parliament.uk/research-briefings/cbp-10495/; https://progressaccountants.com/blog/uk-spring-statement-2026-economic-forecasts-explained/. Reasoning: The falsification criteria state: if the Spring Statement forecast is 0.5pp or more LOWER than Autumn 2025, the prediction is FALSE; if less than 0.5pp downward, flat, or upward, the prediction is TRUE (confirmed). The OBR cut its 2026 GDP forecast from 1.4% to 1.1%, a reduction of exactly 0.3 percentage points. Since 0.3pp < 0.5pp, the revision falls within the confirmed range. The prediction is therefore confirmed with high confidence based on official OBR documents.