premise: Artpop only sold about 100,000 copies.
hypothesis: Artpop . The album received generally mixed reviews from music critics , but was commercially successful , debuting at number one on the United States Billboard 200 with first-week sales of 258,000 copies , becoming Gaga 's second consecutive number-one record in the United States and selling 757,000 copies . Artpop was the ninth best seller album of 2013 with 2.3 million copies worldwide .