Research Ch 11 - Appraising Sampling and Data Collection in Qualitative Studies

Sampling in Qualitative Research

• Qualitative researchers are as concerned as quantitative researchers with the quality of their samples, but they use different considerations in selecting study participants.

• Selection of sample members guided by desire for information-rich data sources

• “Representativeness” not a key issue

• Random selection not considered productive

• Just want to make sure the person has experience with the topic so we can ask questions

Convenience (volunteer) sampling

• not preferred approach but economical

• whatever is in front of you

Snowball sampling (network sampling):

• Sample might be restricted to a small network of acquaintances.

• doing study on students and students tell other student about the study

Purposive sampling:

• Researchers deliberately choose the cases that will best contribute to the study.

Theoretical sampling:

• involves decisions about where to find data to develop an emerging theory optimally

• create theory from research

Types of Purposive Sampling in Qualitative Research

• Maximum variation sampling

• Extreme/deviant case sampling

• Typical case sampling

• Criterion sampling

• Confirming and disconfirming cases

Theoretical Sampling

• Preferred sampling method in grounded theory research

• Involves selecting sample members who best facilitate and contribute to the development of the emerging theory

Sample Size in Qualitative Research

• No explicit, formal criteria

• Sample size determined by informational needs

• Decisions to stop sampling guided by data saturation

  • Data saturation = too many people saying the same stuff over and over

• Data quality can affect sample size.

Ethnography Sampling

• Mingling with many members of the culture—a “big net” approach

• Multiple interviews with smaller number of key informants

• Typically involves sampling things as well as people

Phenomenology Sampling

• Relies on very small samples (often 15 or fewer)

• Two principles guide sample selection

  • Participants must have experienced phenomenon of interest.

  • They must be able to articulate what it is like to have lived that experience.

• May sample artistic or literary sources

Grounded Theory Sampling

• Typically involves samples of 20 to 30 people

• Selection of participants who can best contribute to emerging theory (usually theoretical sampling)

Critically Appraising Qualitative Sampling Plans

• Appropriateness

• Adequacy

• Transferability

Data Collection in Qualitative Studies

• Data collection methods may change as study progresses.

• In-depth interviews most common method

• Observation also common

Unstructured interviews

• Conversational, totally flexible

• Use of grand tour questions

Semi-structured interviews

• Use of a topic guide

Focus group interviews

• Interviews in small groups (5 to 10 people)

• Led by a moderator

Diaries

• Source in historical research

• Provide intimate detail of everyday life

Photo elicitation

• Interview stimulated and guided by photographic images

• Photovoice: asking participants to take photos themselves and interpret them

Qualitative Observational Methods

• unstructured observation in naturalistic settings

  • Can’t be structured because we don’t know what will happen

• Includes participant observation

Gathering Qualitative Self-Report Data

• Researchers gather narrative self-report data to develop a construction of a phenomenon that is consistent with that of participants.

• This goal requires researchers to overcome communication barriers and to enhance the flow of information.

Gathering Participant Observation Data

• The physical setting

• The participants

• Activities

• Frequency and duration

• Process

• Outcomes

Recording Observations

• Logs (field diaries)

• Field notes

  • Descriptive (observational) notes

  • Reflective notes

    • Researcher’s personal experiences

    • Reflections

    • Progress in the fields

Evaluation of Unstructured Observational Methods

• Excellent method for capturing many clinical phenomena and behaviors

• Observers may lose objectivity in sampling, viewing, and interpreting observations.

• Emotional involvement might become a concern.

• Researchers in their member role may develop a myopic view on issues of importance to the group.

  • narrow minded

• The success of participant observation depends on the observer’s observational and interpersonal skills.