In 2005 and 1997, new methods for estimating R&D in universities were introduced, resulting in breaks in series in the higher education sector and the national total.

In 1998, reclassification of an enterprise from one industry to another explains much of the decline in BERD performed in the Office machinery and computer industry.

As from 1991, extramural expenditure is collected separately in Italian R&D surveys and can thus be excluded from most data.

Until 1990, the data for Gross domestic expenditure on R&D by sector of performance and source of funds - were based on all intramural and extramural R&D expenditure (including extramural expenditure abroad). In relation to the Frascati Manual recommendations, the inclusion of extramural R&D expenditure leads to gross domestic expenditure on R&D (GERD) being overestimated. This relates most particularly to R&D expenditure by the business enterprise sector, but concerns the government sector as well.

Extramural expenditure represented:

-      At national level, over 6 % of GERD in 1991 and some 15 % in 1993. In 1991, over 20 % of such extramural expenditure represented financing abroad; in 1993, over 26 %.

-      For the business enterprise sector, 11 % in 1991 and around 15 % in 1993 of its R&D expenditure (BERD). Over 13 % in 1991 and around 18 % in 1993 of R&D financed by the business enterprise sector was extramural expenditure (a quarter of the sector's extramural expenditure represented payments abroad).

-      For the government sector, only 1 % of its R&D expenditure (GOVERD).

As from 1987, the breakdown of R&D expenditure by type of R&D is based on total expenditure and not current expenditure on R&D.