Introduced on day 26
Exchangeability
The property that the joint distribution of a set of observations does not change when their order is shuffled; the assumption behind standard conformal coverage.
In detail
Independent and identically distributed data are exchangeable. Time series with seasonality, trend or regime changes are not, because the position in time carries information about the error distribution. Checking it means comparing errors across periods and asking whether the calibration pool looks like the period being forecast.