Paradoxo do Custo de Vida em Angola: validação externa do ARIMA (0,2,2)

This article analyses the gap between the deceleration of official inflation in Angola (14.56% in January 2026) and the persistence of high prices for essential goods: the Cost-of-Living Paradox. The ARIMA(0,2,2) model is submitted to external validation on the IPCN series from December 2015 to August 2026, under a declared protocol. In the recursive validation (n = 56) the mean absolute error was 0.30 percentage points and the mean absolute percentage error (MAPE) 1.63%, outperforming six naive benchmarks (Diebold-Mariano, p < 0.001); strictly out of sample (n = 8, information fixed in December 2025) the MAPE rises to 4.58%, with the coverage of all eight intervals and a bias of +0.52 percentage points. The cost of living in Luanda is then characterised with Numbeo unit prices (6 October 2026): the rent of a three-bedroom apartment in the city centre absorbs 152.0% of the average net salary and the budget of a family of four excluding rent amounts to 161.4% of that salary. The deceleration of inflation coexists with a price level that a single average net salary does not cover in the reference budget of a middle-income household, and independent modelling subjected to validation is useful but limited in scope.