If your evaluation questions are focused on relationships, subjective perceptions or people’s understandings of their own experiences, then interpersonal methods of data collection may be the best way to go. Also called qualitative methods, these approaches elicit open-ended responses and allow respondents to describe their experience in their own words.
Focus groups typically take place in-person (although other formats, such as online groups are increasingly common). Personal interviews may take place either face to face or over the telephone. Both approaches typically use an interview guide in order to keep the conversation on track although the degree to which the interviewer or moderator sticks to the guide depends upon the nature of the evaluation questions being asked.
In order to gather unbiased data, personal interviews and focus groups are best conducted by third parties. First, respondents are much more likely to speak candidly to some one who is not personally involved in the program being assessed. Second, interviewing and focus group moderation are both specialized skills that require experience to do effectively.
One last note: Sometimes inexperienced moderators conduct focus groups as if they are group interviews. Often the impetus is to save time by bringing a group of interviewees together at one place and time. While group interviews can yield useful information, what makes a focus group unique is the interaction between the participants. Make sure your moderator understands the distinction between a focus group and a group interview before your project gets started.