Complex sentence: Arthur Charles Nielsen, Sr. (September 5,1897--June 1,1981) was a U.S. market analyst.Of Danish descent, he was the founder and eponym of the ACNielsen company in 1923, and in doing so advanced the new field of marketing research.
Split into simpler sentences: Arthur Charles Nielsen, Sr. (September 5,1897--June 1,1981) was a U.S. market analyst. He was the founder and eponym of the ACNielsen company in 1923, and in doing so advanced the new field of marketing research.