As suggested previously, standardisation is achieved in national accounts series by compliance with 2008 SNA or ESA 2010. Comparisons are best made within the convention, although the structure of the ESA 2010 is consistent with the worldwide guidelines on national accounting set out in 2008 SNA, and ESA 1995 is compatible with 1993 SNA.
Some historical series in follow different, perhaps earlier conventions (e.g. 1968 SNA). Check for this as problems may well arise in making comparisons with series produced under the current conventions (as above).
In most publications, disaggregated data for economic activity by industry is obtained using ISIC Rev.4 or its European counterpart NACE Rev. 2 (that operates with the same classification system as ISIC but with greater precision).
But ISIC Revision 3 series are to be found in the databank. Check for comparability with Revision 4.
The OECD is at the forefront in producing harmonised data. Its STAN database (STructural ANalysis Database) recommends itself for use in making comparisons in many areas including disaggregated data based on ISIC. STAN also contains harmonised Input-Output tables.
Aggregated national account series in PPP (see later section) format are published in the the World Bank World Development Indicators and in the OECD National Accounts Comparative Tables Based on exchange Rates and PPPs (and other tables).
Social expenditure for OECD countries, at purchasing power parity (PPP), can be found on the organisation's Social Expenditure Database.
Use OECD and World Bank databanks to find well harmonised series. Eurostat also contain harmonised series.
