  International collaboration is sometimes encouraged in the belief that it
generates higher quality research or is more capable of addressing societal
problems. Nevertheless, while there is evidence that the journal articles of
international teams tend to be more cited than average, perhaps from increased
international audiences, there is no science-wide direct academic evidence of a
connection between international collaboration and research quality. This
article empirically investigates the connection between international
collaboration and research quality for the first time, with 148,977 UK-based
journal articles with post publication expert review scores from the 2021
Research Excellence Framework (REF). Using an ordinal regression model
controlling for collaboration, international partners increased the odds of
higher quality scores in 27 out of 34 Units of Assessment (UoAs) and all Main
Panels. The results therefore give the first large scale evidence of the fields
in which international co-authorship for articles is usually apparently
beneficial. At the country level, the results suggests that UK collaboration
with other high research-expenditure economies generates higher quality
research, even when the countries produce lower citation impact journal
articles than the United Kingdom. Worryingly, collaborations with lower
research-expenditure economies tend to be judged lower quality, possibly
through misunderstanding Global South research goals.
