Google Research Scientist interview questions

They made initial contact via email, then face to face over Hangout. After this I was invited for a 'Quiz' which I was told would last 2 hours. It was on Stats, Math, Computer Programming and Machine Learning. It took 4 hours in total. A week later I was told that for the current open positions they needed someone stronger at math, so to get in touch when I felt more confident. I'm in the process of brushing up my math.

Initially talked to HR on the phone who contacted me soon after I submitted my application--wrote to a scientist at Google. Then a week later I talked to two different engineers. I did not hear back after that.