  This paper presents a statistical analysis of the relationship between three
science indicators applied in earlier bibliometric studies, namely research
leadership based on corresponding authorship, international collaboration using
international co-authorship data, and field-normalized citation impact.
Indicators at the level of countries are extracted from the SIR database
created by SCImago Research Group from publication records indexed for
Elsevier's Scopus. The relationship between authorship and citation-based
indicators is found to be complex, as it reflects a country's phase of
scientific development and the coverage policy of the database. Moreover, one
should distinguish a genuine leadership effect from a purely statistical effect
due to fractional counting. Further analyses at the level of institutions and
qualitative validation studies are recommended.
