Documentation/ Guides / Working with the data / 22 of 25
How the statistics are made
The method behind every statistic, what each needs, and where each one stops.
Guide
Every statistic is worked out each night from the published figures we hold, never from anyone else's model. A country only carries a statistic it has the history for; /v1/countries/{iso} lists which.
Statistic
Method
Needs
Trend
Multiplicative decomposition, 2x12 centred average
60 unbroken months
Recovery
Month against the same month of 2019
2019 held
Benchmark
Yearly index, 2019 = 100, against the region
Whole years, 3 peers
Forecast
Holt-Winters on logs, damped slope, fitted from reopening
36 months since reopening
Nowcast
Same month last year times the recent year-on-year change
A forecastable series
Anomalies
Remainder after trend and season, robust standard deviations
Trend
Origin shift, concentration
Shares of the latest 12 months against the 12 before
5 or more monthly markets
Forecasts are tested every night on the last 12 published months, and that error is returned with every forecast. Where it is high, it is shown, not hidden.
A nowcast is an estimate and always says so. It is replaced by the published figure the moment the office releases it.
