Types of interviews

As part of this ongoing course, I had to arrange an interview with a person in an organization to understand the link between organizational strategies and portfolio management. For a big and diverse organization, the higher interviewee's position in the management, the better one can understand the linkage.
However, we all face the same dilemma in our work lives: we don't have time.
So even if you manage to get hold of any executive for a personal interview, you have to ensure that the interview is conducted in such a way that all aspects of the interview is covered in the allocated time budget. This means that the conversation has to be steered in a way to avoid too many deviations or diversions. This is an interview type that is called semi-structured interview.

What are the other interview types. According to Wikipedia:

Structured interviews are a means of collecting data for a statistical survey. In this case, the data is collected by an interviewer rather than through a self-administered questionnaire. Interviewers read the questions exactly as they appear on the survey questionnaire. The choice of answers to the questions is often fixed (close-ended) in advance, though open-ended questions can also be included within a structured interview. A structured interview also standardizes the order in which questions are asked of survey respondents, so the questions are always answered within the same context. This is important for minimizing the impact of context effects, where the answers given to a survey question can depend on the nature of preceding questions. Though context effects can never be avoided, it is often desirable to hold them constant across all respondents.
 
An unstructured interview or non-directive interview is an interview in which questions are not prearranged. These non-directive interviews are considered to be the opposite of a structured interview which offers a set amount of standardized questions. The form of the unstructured interview varies widely, with some questions being prepared in advance in relation to a topic that the researcher or interviewer wishes to cover. They tend to be more informal and free flowing than a structured interview, much like an everyday conversation.

A semi-structured interview is a method of research used most often in the social sciences. While a structured interview has a rigorous set of questions which does not allow one to divert, a semi-structured interview is open, allowing new ideas to be brought up during the interview as a result of what the interviewee says. The interviewer in a semi-structured interview generally has a framework of themes to be explored.
However, the specific topic or topics that the interviewer wants to explore during the interview should usually be thought about well in advance (especially during interviews for research projects). It is generally beneficial for interviewers to have an interview guide prepared, which is an informal grouping of topics and questions that the interviewer can ask in different ways for different participants. Interview guides help researchers to focus an interview on the topics at hand without constraining them to a particular format. This freedom can help interviewers to tailor their questions to the interview context/situation, and to the people, they are interviewing.

 Reference:
(1). https://en.wikipedia.org/wiki/Structured_interview
(2). https://image.slidesharecdn.com/interviewingrevised-150621191838-lva1-app6891/95/interviewing-4-638.jpg?cb=1434914365