The 668 papers on hierarchical modeling included 2541 authors (median number of authors per paper = 3, IQR = 2-5). The top 10 most productive authors are listed in Table \ref{889877}. Most authors (50.69%) were affiliated with institutions in the USA. The top 10 countries by number of authors are followed by UK (4.48%), Australia (3.87%), Canada (3.62%), Germany (2.85%), Brazil (2.68%), Italy (2.52%), South Africa (2.36%), Spain (2.03%) and Switzerland (1.91%).