A correction calculation method for a satellite based positioning system with a network of receiving units as reference stations comprises a partitioning of the network into groups of reference stations, calculation of group-specific correction factors, amalgamation of the group-specific correction factors and subsequently, derivation of network-specific correction parameters. In this partitioning, the reference stations are represented by nodes in a connected, edge-weighted graph, in the generation of which an edge respectively connecting two nodes is only generated if it satisfies a distance-dependent connectivity condition, whereby the distance between the nodes connected by this edge is input into the weighting function of this edge. From the graph a minimum spanning tree is derived and subsequently partitioned for establishing the groups.