Version 1. Forecasts are computed once a month, on the 6th (Türkiye time), from the months before. A run is never changed afterwards.
What is forecast
For each product group (four-digit HS heading) and destination country: how many distinct buying needs will appear in each of the next three months, with an 80% band around each figure.
What counts as demand
- Public tenders, foreign buying opportunities and official investment-incentive records that name the heading.
- Needs members published to everyone on Birlesa.
- Not needs that members shared only with suppliers or kept private. Nothing a member did not publish can be read from a forecast.
- One need counts once per heading and month, whatever its quantity. The destination is where the goods go: the buyer's country, or the export destination the buyer named.
- A series is considered only with at least 12 needs over the last 36 months.
The method
Damped-trend exponential smoothing (Holt's method with Gardner and McKenzie's damping): a level and a trend, updated each month, with the trend fading over the forecast horizon so that forecasts do not run away. Its three parameters are chosen from a fixed grid by the error of one-month-ahead predictions over the history.
Backtesting: only forecasts that earn their place
Before a series is published, the method is tested on its own past: from each of the last six months it forecasts up to three months ahead, using only what was known then, and its errors are compared with those of the simplest forecast ("next month will be like the last"). A series is published only when the method's absolute error is lower. The ratio is published with it (relative_error, below 1).
The bands
The band around each forecast covers 80% of outcomes, under the assumption that errors behave like the method's past one-month errors, widening with the square root of the horizon. Counts never go below zero.
Early warnings
When next month's lower band is above one and a half times the heading's usual level (its average over the last 12 months, at least two needs a month), the forecast is marked rising. Organizations whose company pages list products under that heading are told by e-mail, if they agreed to receive alerts, at most three headings each per month.
Limits
- Needs on Birlesa and official records are a sample of the market, not all of it. Customs statistics and search interest will be added as further inputs when they are available.
- A sudden change with no sign in the past (a new regulation, an embargo) cannot be foreseen by this method.
- A forecast is a statement about likelihoods, not a promise. Weigh it with what you know.
Changes to this method
Any change gets a new version number, is described here, and applies from the next run; past runs keep the version they were computed with.