GDP 3-Month Avg

GDP Three-Month Average is the headline figure of the GDP monthly estimate bulletin for the United Kingdom. It compares average output across a three-month period with the previous three-month period in chained volume, or inflation-adjusted terms. Output means gross value added, or GVA, which covers services, production, construction and agriculture.

It measures real growth, not cash or nominal growth, and it uses GVA as a proxy for GDP. GVA at basic prices plus taxes on products less subsidies equals GDP at market prices. So monthly GVA can differ slightly from true monthly GDP. It differs from quarterly GDP, GDP per head and spending-based or income-based measures, and it gives a rapid view of trend.

ONS, the UK statistics agency, publishes one bulletin each period around 40 days after period end. Each bulletin reports single-month growth and three-month growth and points to services, production and construction bulletins plus detailed datasets. Datasets include monthly GVA tables, contributions to growth and time series with revisions triangles and industry detail.

Revisions normally cover only the months of the reference quarter as survey and tax-reported sales responses arrive. Early estimates are revised up and down in subsequent bulletins as responses complete and seasonal factors are re-estimated. Annual Blue Book reconciliation can revise earlier periods and widens the window with quarterly GDP. Reading is directional: positive signals expansion and negative signals contraction, with no buy or sell threshold published.

Sectors combine by published GVA weights to shift the headline, with services dominant by far.

• Services, 79.8%: broad consumer, business and public services, from retail to finance, property, health and education, and the dominant driver of most moves.
• Production, 13.5%: goods output spanning manufacturing, mining, energy supply and water and waste, capturing goods swings.
• Construction, 5.9%: building work covering new projects plus repair and maintenance, led by private housing swings, with Great Britain coverage.
• Agriculture, 0.7%: farming, forestry and fishing, a small residual with little headline impact.

1. Collect output: gather sales at market prices from Monthly Business Survey, plus construction, tax turnover and models for gaps.

1. Deflate to real terms: strip inflation with CPI, PPI and SPPI price parts to leave chained-volume GVA, or inflation-adjusted value added.

1. Seasonally adjust: remove calendar and time-of-year effects to leave trend plus irregular noise.

1. Index and weight: express each series as an index, or scaled level, then combine with GVA weights.

1. Compare means: divide the mean index of a three-month period by the prior three-month mean, subtract one and express as percent. For example, means of 100.10 and 100.40 give about 0.3%.

Report growth to one decimal place and do not read direction from extra digits when growth shows as no change.