The Research Outputs Database (ROD) has been used to investigate the e
ffects of different input variables, including the numbers of funding
bodies, on the impact of research papers in a biomedical subfield (gas
troenterology). This was determined by the medium-term impact of the j
ournals in which they were published. It was shown that, when account
was taken of the effects of the other input factors, the mean impact f
or a group of papers increased with the number of authors, the type of
research (basic more than clinical), and with the number and identity
of the funding bodies. However it decreased slightly if there were mo
re addresses; whether the paper was multinational had no significant e
ffect. Previous work showing that multi-institution or multi-country p
apers are more highly cited reached this conclusion because it did not
take into account the confounding effect of multiple funding sources,
and possibly other factors.