There are a number of collection requirement methods associated with project scope management. Two collection requirements include interviews and focus groups. Interviews have a few advantages, such as real-time follow-up questions and further discussion, as well as non-verbal cues that can only be observed when in person. Some disadvantages include the personal bias of the interviewee and the reliance upon the interviewers skills. Focus groups have similar disadvantages in that they also require reliance on the expertise of the moderator, and there could be biases that may hinder the results. Some advantages of the focus groups would be that several requirements can be collected in a short period of time (2017). 
I believe that a key to the success of a project manager is often delegation. I think that the project manager should oversee all aspects of a project. However, it is more important to have trusted team members who can carry out the necessary tasks involved. I believe that the business analyst should fulfill the role of requirement collection. The more they do so, the more likely they will gain expertise in collection requirement methods.