Step 1: Decide on the appropriate level of structure, planning ahead of time what topics and questions to cover while also allowing for open-ended opportunities.

An interview allows you to gather systematic information about a project and also respond to the unique perspectives and priorities of each individual being interviewed. Deciding on the right balance between these approaches depends on the purpose of the interview. If you are interested primarily in participants' perspectives that you do not think you can anticipate, then a less structured interview is called for. Here the expectation is that the situation is somewhat unfamiliar to the interviewer and that participants may generate or identify useful ideas about potential variables or relationships on their own. If you are interested in being able to study patterns of relationships in a more familiar situation, you will want different participants to respond to the same sets of questions. This approach implies using a more structured interview. Two examples of situations contrasting the need for more versus less structured interviews are given below.

Situation Calling for a Less Structured Interview. You are in the formative stage of an evaluation and want to understand why project staff are receiving many calls from participants asking for clarification and indicating their frustration with trying to implement the project. You want to ask each interviewee about all the major implementation components, so you write out several broad protocol questions to include in all interviews. However, you want to devote most of the interview to exploring each interviewee's own views of the implementation process and obstacles. Here, you again can plan a few common questions that can lead each participant into this focus (e.g.,"Please tell me about anything that has made using this project difficult."). Your main strategy will be to let the participants' perspectives guide the remainder of the interview, calling for follow-up and probing questions that may be unique to each participant.

Situation Calling for a More Structured Interview. You are evaluating a new curriculum, and you want to conduct a set of interviews that lets you compare the attitudes of teachers and students toward the curriculum. Because you know exactly what the curriculum consists of and you want to directly compare the responses of teachers and students, you plan two structured interview protocols (one for teachers, one for students) in which most questions are predetermined and common to both protocols. Of the common questions, most still are open ended (meaning you will have to categorize, code, and then compare responses). You also decide to include several closed-ended items asking each group to rate different aspects of the curriculum. Including these will eliminate the need for a separate questionnaire.

It is important to note that interviewer control is independent of the level of interview structure. In the context of evaluation interviews, the interviewer needs to maintain control of the interview regardless of how much the participants' perspectives are guiding the interview content. Maintaining control means setting the pace of the interview so that all essential information can be covered in the allotted time (see Administering Interviews). Also, even with a very free-flowing, open-ended interview, it means coming prepared with a consistent approach to wording questions so as to communicate the professionalism and neutrality of the interviewer.