Peering into the Present: The Bank's Approach to GDP Nowcasting
Bibliographic record
Abstract
The Bank’s GDP nowcast represents the Monetary Policy Committee’s (MPC’s) estimate of economic growth in the current quarter, before official data become available. The nowcast is informed by statistical models, but is ultimately judgemental, reflecting all available information. Users of nowcasts must be aware of the degree of accuracy that can be expected, as this varies across models and time. Models based on survey information tend to be more accurate early in the quarter, whereas high‑frequency output data published by the ONS become more useful later. The MPC’s Inflation Report nowcasts have been relatively accurate, with a root mean squared error of 0.3 percentage points over the past ten years - lower than a mechanical use of the models could have attained. GDP growth estimates have fallen within 0.1 percentage points of the MPC’s expectation about half the time, although much larger surprises have occasionally occurred.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.074 | 0.287 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.006 | 0.007 |
| Science and technology studies | 0.005 | 0.004 |
| Scholarly communication | 0.022 | 0.014 |
| Open science | 0.003 | 0.006 |
| Research integrity | 0.006 | 0.011 |
| Insufficient payload (model declined to judge) | 0.014 | 0.004 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".