I forgot when I submitted the application and online assessment problem. The serious interview has two rounds, both very technical. First round asked about my experiences, dived very deep into projects, and asked methodologies regarding statistics, probability theory, optimization. Problems focus on methodology and approaches, no quantitative analysis. Interviewer has great knowledge depth, also asked the cutting-edge questions in the research field, to test my ideas and knowledge. The interview ended with a case study. Interviewer provided a scenario, and asked me to define the problem, variables, general ideas of formulations, constraints, bottom necks, protential implementation challenges and solutions. Second round involves one leetcode style questions, easy level, longest common element. Typical behavior questions. How do you make sure delivery with ambiguous requirements. Provide project experience where your supervisor decided to change the goal in the middle of process.

BQ is easy but the research question is hard for me. So I do not get the offer. Maybe I will do hard next time for a better result to get an offer.