The internal recruiter got back to me a day after I had submitted my application. She turned out to be incredibly helpful throughout the entire interview process, answering all my questions and even sending me an overview of the topics I'd be going over in my other interviews. This was really the best interview process I'd ever gone through, due in no small part to the care the company took in communicating with me throughout each step of the process. They were very transparent with everything, and I appreciated that immensely. The entire interview process consisted of:
1) Phone interview with recruiter (this functioned as both an informative overview of the role/Quantcast and an interview)
2) Quantitative exercise (in lieu of a presentation)
3) Phone interview with manager
4) In-person interview with team members (totaling two hours)
5) Phone interview with a senior manager
6) Offer extended
7) Checked references and performed a background check after acceptance of the offer
The interview was very thorough--definitely more of a high-level conversation than a hard-hitting question and answer session. Above all, they want to see that you're dedicated, curious about the position and Quantcast's work, and a solid fit for the role. I'd advise on bringing a lot of questions with you to each stage of the process and making sure you get an in-depth picture of the position.