美国知乎挂经，求大米！

申请的是ds岗位，面试的小姐姐很nice地walk through了问题，还给了hint，但是因为在product sense方面没有好好准备，挂的很直接。。。周五面的，周一一大早就愉快地发了据信
面经，求大米求大米！

1). Time to run an experiment2). DS do find that reading time for “answers” increased in the experiment group, but time for “questions” decreased. Can you think of potential reasons for this? And how can you validate.
3). DS want to know if the anti-correlation between time in “answers” and “questions” is a general trend, regardless of the experiment. How can you validate this