Sampling for interviews and focus groups

The priority for sampling in qualitative data collection is to hear a diverse range of views from multiple perspectives. The aim is not to generalise from a small sample to the broader population.

Adequate sample coverage may require the use of different approaches with different groups in the target audience, such as small group interviews with teachers and focus groups with parents. You may also need to specifically invite people who are less likely to respond.

Adequate sample size will ensure that analysis is not based on just one or two voices. Rigorous qualitative data collection keeps going until the point of theoretical saturation, at which analysis of additional data provides no new insight into the issues being investigated.

Structure and control

All data collection in evaluation needs to be purpose-driven, with a clear set of research objectives.

Structured interviews require the interviewer to ask pre-written questions in the same way and same sequence for each respondent or group of respondents. This is helpful for less experienced interviewers and where more than one person is collecting the data.

Semi-structured interviews are still governed by a discussion guide, but the interviewer has more flexibility about the order in which topics are discussed and the phrasing of questions. This allows for a more natural conversational flow and lets the interviewer explore topics that emerge during the discussion. This format requires the interviewer to have a high level of skill and a deep understanding of the research objectives.

Unstructured interviews are uncommon in evaluation, with the exception of focus groups. The intent of a focus group is to spark interaction within the group to stimulate ideas and comments around a given topic of discussion. This environment enables participants to ask questions of each other, as well as to re-evaluate and reconsider their own perspective on specific ideas or experiences during the course of the discussion.

Group size and composition

Interviewing people individually gives each participant an equal opportunity to have their say, in private. This is particularly useful when:

• the topic is sensitive or confidential
• communication assistance is required (for example, translation)
• participants are experts in their field or the line of inquiry is narrow
• it’s not practical to get people together in the same room.

Group interviews and focus groups can be undertaken with groups as small as 2-3 people, up to a maximum of 9-10 people. Any larger than that, and the facilitator will need to use a different set of workshop strategies to allow participants to have their say. Semi-structured group interviews tend to become unwieldy with more than 4-5 people. Most focus groups consist of 6-10 participants.

It is important for all participants in the group to have an equitable opportunity to participate.

• Questions need to be phrased to elicit full responses by all participants. The facilitator may have to encourage certain group members to speak up or make space for all to contribute.
• The larger the group size, the fewer the questions that can be asked. Questions must be carefully prioritised.
• Discussions tend to run more smoothly if participants are somewhat homogenous in the context of the evaluation, for example, primary teachers, parents of students in the school band, Year 11 students doing VET courses.
• Skilled facilitators may also gain insight from assembling small groups (2-3 people only) based on discontinuity, for example, three parents from the same primary school who sent their children to different high schools in the local area.

Communication channels

Selection and preparation of the team

Interviews and focus groups can be conducted by teachers, people within the school or someone external, for example a teacher from a partner school or a colleague from state office.

Attributes that help ensure a quality interview include:

• strong interpersonal and communication skills, with the ability to build rapport quickly so that respondents feel at ease and speak freely
• familiarity with the topic and context, with a good understanding of what the questions are asking
• neutrality wherever possible. Avoid having an interviewer who has a vested interest in the outcome of the evaluation
• the ability to be non-judgemental and sensitive when dissenting or unconventional views are expressed
• knowledge of how to deal with interviewee distress, negative reactions and so on.

When deciding who will undertake the interviews, it is also important to be sensitive to possible power dynamics. For example, you may want to organise groups so that teacher focus groups are not being facilitated by the people who directly supervise them.

Conducting interviews and focus groups with students

When planning qualitative data collection with students, it’s important to consider:

• child protection – focus groups and interviews should ideally be conducted by two facilitators, or one facilitator and one observer or note taker. In some contexts, it may be advantageous to match gender with the students - male interviewers for male students, female interviewers for female students. Anyone coming into contact with students needs to have the appropriate NSW Working with Children clearances.
• group size – one-to-one interviews are not recommended with students, who often respond with more confidence when accompanied by others. If interviewing a mixed-age group, it’s good to include pairs of students of a similar age or from the same stage.
• cultural safety – when interviewing Aboriginal students, an Aboriginal Education Officer or a member of the local Aboriginal community, such as a member of the AECG, should be involved.
• location – choose a safe, familiar setting that is visible to others but has sufficient distance from others. Examples include the school library or an area of the classroom separated from class activities.
• trust – confidentiality of responses is often important to students, and it’s important to keep reassuring them that the interview is in confidence, and others will not know what they say.
• agency – within the topic of interest, acknowledge the value of the students volunteering information and talking about what is important to them.
• duration – keep small group interviews (2-3 students) to 30 minutes, with some flexibility to respond to the conversation. Larger group discussions can run for longer, dependent on the age of students: 20-30 minutes for kindergarten students, generally no longer than one period in secondary.