Arnoldo Frigessi di Rattalma (born 1959) is an Italian statistician based in Norway, where he is a professor at the Department of Biostatistics (now called Oslo Centre for Biostatistics and Epidemiology) with the Institute of Basic Medical Research at the University of Oslo.
He has also a position at the Oslo University Hospital and is affiliated with the Norwegian Computing Centre.
Frigessi succeeded in obtaining funding for a second centre of the same type, BigInsight, which started in 2014 and will operate for 8 years, again under his leadership.
Frigessi develops new methods in statistics and machine learning and stochastic models to study principles, dynamics and patterns of complex dependence.
In 2021 he received the Sverdrup Prize from the Norwegian Statistical Association, elected Fellow of the Institute of Mathematical Statistics and is knighted Cavaliere Ordine al Merito della Repubblica Italiana.