noun
statistician
A person who specializes in statistics, either as an academic or a professional.
彼は大学で統計学者として働いている。
He works as a statistician at a university.
統計学 is the field of statistics, while 統計学者 is a person who practices or studies it.
Compound of 統計 (statistics) + 学 (study) + 者 (person).