Onward Search interview question

Q: Tell me about a complicated SQL query you wrote? How did you optimize the join query? Did you use window function or indexing method? Q: What library did you use for coding in R or Python? Walk me through how did you use that library to perform analysis? Q: Tell me about your ML model project? How did you decide training and test set? Q: Explain A/B testing for me in simple words? Aside from the metric your mentioned, what other success metrics did you track to evaluate the experiment? Q. Tell me about a time you communicated with non-technical audience? What follow-up questions did they raise and how did you answer them?