  Open Access (OA) facilitates access to articles. But, authors or funders
often must pay the publishing costs preventing authors who do not receive
financial support from participating in OA publishing and citation advantage
for OA articles. OA may exacerbate existing inequalities in the publication
system rather than overcome them. To investigate this, we studied 522,411
articles published by Springer Nature. Employing correlation and regression
analyses, we describe the relationship between authors affiliated with
countries from different income levels, their choice of publishing model, and
the citation impact of their papers. A machine learning classification method
helped us to explore the importance of different features in predicting the
publishing model. The results show that authors eligible for APC waivers
publish more in gold-OA journals than others. In contrast, authors eligible for
an APC discount have the lowest ratio of OA publications, leading to the
assumption that this discount insufficiently motivates authors to publish in
gold-OA journals. We found a strong correlation between the journal rank and
the publishing model in gold-OA journals, whereas the OA option is mostly
avoided in hybrid journals. Also, results show that the countries' income
level, seniority, and experience with OA publications are the most predictive
factors for OA publishing in hybrid journals.
