The world according to GaWC is a city-centred world of flows in contrast to the more familiar state-centred world of boundaries.
Cities are assessed in terms of their advanced producer services using the interlocking network model (see GaWC Research Bulletin 23). Indirect measures of flows are derived to compute a city's network connectivity – this measures a city's integration into the world city network.
The connectivity measures are used to classify cities into levels of world city network integration. These levels are interpreted as follows:
alpha++ cities In all analyses, London and New York stand out as clearly more integrated than all other cities and constitute their own high level of integration
alpha+ cities Other highly integrated cities that complement London and New York , largely filling in advanced service needs for the Pacific Asia
alpha & alpha- cities Very important world cities that link major economic regions and states into the world economy
All beta level cities These are important world cities that are instrumental in linking their region or state into the world economy
All gamma level cities These can be world cities linking smaller regions or states into the world economy, or important world cities whose major global capacity is not in advanced producer services
Cities with sufficiency of services These are cities that are not world cities as defined here but they have sufficient services so as not to be overtly dependent on world cities. Two specialised categories of city are common at this level of integration: smaller capital cities, and traditional centres of manufacturing regions
NOTE: the classifications used here are based upon relational measures and should not be confused with the initial use of alpha, beta and gamma categories for 1998 data that used simple attribute measures. These early results are not comparable with the results for 2000, 2004, 2008, 2010 and 2012 presented here.
For a first analysis and interpretation of the new classification, see GaWC Research Bulletin 300.