Their technical interview is no joke. It is long, covers a wide range of topics and is not something that you can cram for prior to the interview. They don't really give you an idea of what they will ask beyond "questions about statistics and predictive modeling" which can include a lot.

Not a great experience in any way. Recruiter only communicated via text, and tried to rush me to the first phone call. Then showed up 10 minutes late to call and proceeded to talk at me the entire time without room for questions from me. Told me how my resume matched exactly what they were looking for and wanted to get me to the next step as fast as possible. After they had shared the comp details, which I said that worked for my expectations, they then pressed many times to get my exact current compensation. I chose to not share and just reiterated the range they shared is good with me (it's illegal in both my location and where Root is located to ask about previous compensation). The recruiter then abruptly hung up and didn't get back to me for a couple weeks, eventually telling me they wanted someone with a different profile. Too many red flags - would not apply here again.