MODELING AND MEASURING MULTILATERAL CO-AUTHORSHIP IN INTERNATIONAL SCIENTIFIC COLLABORATION - PART-I - DEVELOPMENT OF A NEW MODEL USING A SERIES EXPANSION APPROACH

International co-operation has strongly intensified during the last de cades owing to rapid developments in scientific communication. Economi c, political, and intra-scientific factors also strongly influence int ernational collaboration links among individual countries. Obviously r esearch results of international scientific co-operation are reflected in the documented scientific communication as international co-author ship links in scientific publications. Most bibliometric studies on th is issue pertain to the share of international co-authored papers in n ational publication output and their impact on national and internatio nal research, or to the analysis and mapping of the structure of colla boration links. The present study attempts to develop a model to measu re and analyse the extent of multilateral international co-authorship links. A new indicator, the Multilateral Collaboration Index (rho) is introduced and analysed as a function of the share of internationally co-authored papers (f). Based on f a series expansion approach is appl ied that can be considered an extension of a fractionation model by Ne derhof and Meed and allows classifying the extent of multilateral link s both among science fields and among individual countries. The paper is concluded by a first attempt to estimate the errors involved in our approach.