2x interviews (20 mins each)
First interview: technical questions. Second interview: more general.
Consolidate current knowledge; mock interview
Keep as calm as you can
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
There were two twenty minute interviews, separated by around an hour. My first interview was conducted by an economics professor and a maths PhD student, and my second interview was conducted by two economics professors. The interviews tested topics in economics I had not encountered before, my maths and logic skills, as well as content from my personal statement.
In my first interview, we discussed production and productivity (including how Brexit could have an impact!). The second question was a maths question, and I was asked to draw a graph. The key to this was to keep explaining what you were doing and thinking even though maths requires a lot of internal processing. The final question was a theory problem.The answer doesn't exist! I was trying to figure it out but couldn't do it, but I made sure to keep communicating. One of the interviewers cut me off when the time limit for the interview was up and asked if I had any questions.
In my second interview, I was first asked about something I had mentioned in my personal statement. I was then asked to come up with formulas for some standard economic concepts. We also touched on the relationship between geographical location and pay.
A lot of this interview was very fast paced and it really is a lot all at one time, so I would recommend keep trying your best, don't get panicked, and to keep a smiling face - even if you think it is going really badly! The interview questions are really tough for everyone and they purposely set questions like that to get you to explain your thinking, and not necessarily reach a final answer.
I would highly recommend keeping up with the news and trying online practice questions--don't try reading tons of new books now; instead consolidate all that you have done. Instead, make a list of everything you have done, whether by reading, lectures or work experience, and really make sure you know what you are talking about in those fields. Also go over your personal statement line by line and make sure you know exactly what you wrote, and that you can explain everything with examples.
I was fortunate to receive aDon't get flustered or fazed by difficult questions, as you should remember that they are difficult for everyone! The professors might try to push you, but you should maintain your composure and go through the entire interview process with a positive mindset--you were fortunate enough to get an interview and now you really don't have anything to lose. You never know what can happen, so don't think your interview is going/went really badly! I thought mine did, and I was shocked when I was put into the winter pool and made an offer by another college.