Well, I don’t think you should start with the case study too early unless you have made full preparation or you might find you can’t meet the deadline. However, it really is the best approach you can try to get people’s response though it is somewhat time-consuming. If you think you can spare your study time, just go for it.
第一句话出现don’t think，转折词However引出了意思上大的转变，这里的it really is the best approach就是很大的一个转折，说明持支持的态度的。此外，最后一句话是总结性的观点，一句just go for it非常清楚地再次表示其支持观点。
Through observation study, you can just watch and take notes. And you can get some unforeseeable results from people’s behavior, but it can only cover certain aspects. Therefore, you need other research method to assist it. But you can try if you want.——中立
Well, I think questionnaires are very good at telling you how people fill in questionnaires, but they tell you very little else. So better avoid it.——反对
Face-to-face interview can help you get people’s facial expressions and body language, through which you can identify what they genuinely have in mind. But it depends sometimes. Not everyone is willing to open his or her mind to you.