In some cases, the sum of the regional/provincial figures was not exactly the same as the national total, which meant that the regional/provincial totals had to be adjusted. These are differences that result from chance errors, from the quality of the regional/provincial data, or from specific differences in the coverage or definition of the national total.

In an attempt to eliminate such differences, the authors made adjustments in proportion to the regional figures, so that the same percentage adjustment would be applied to all regions/provinces. Thus for 1999 the national data showed a difference of 1.2% less than the sum of the regional/provincial figures. In this case, the regional/provincial figures were adjusted by this percentage.

This same criteria was also used to share out the Customs Duties and the Indirectly Measured Financial Intermediation Services (SIFIM) to reach the GDP.