Tier I

Indicator is conceptually clear, has an internationally established methodology and standards are available, and data are regularly produced by countries for at least 50 per cent of countries and of the population in every region where the indicator is relevant.

Tier II

Indicator is conceptually clear, has an internationally established methodology and standards are available, but data are not regularly produced by countries.

Tier III

No internationally established methodology or standards are yet available for the indicator, but methodology/standards are being (or will be) developed or tested. (As of the 51st session of the United Nations Statistical Commission, the global indicator framework does not contain any Tier III indicators)

Tier I/II depending on service

Tier I (a)/Tier II (b)

Tier I Provisional

Tier I/II Depending on indice