I first got a email from HR asked when to arrange an phone interview, the same afternoon she called me. I was asked a few simple questions based on my resume. Then she offered me on an on-site interview 5 days later. The on-site interview consists of HR interview (the same person who gave me the call), asked more questions about my personal background. I felt like she just want to know more about me. And next person came in who asked me some basic math and stats questions.