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Sample Size in Qualitative Interview Studies: Guided by Information Power.

Kirsti Malterud1,2,3, Volkert Dirk Siersma1, Ann Dorrit Guassora1

  • 11 University of Copenhagen, Copenhagen, Denmark.

Qualitative Health Research
|November 29, 2015
PubMed
Summary
This summary is machine-generated.

Determining qualitative study sample size requires "information power," not just saturation. More relevant information per participant means fewer are needed, guided by study aim, specificity, theory, dialogue, and analysis.

Keywords:
information powermethodologyparticipantsqualitativesample sizesaturation

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Area of Science:

  • Qualitative Research Methodology
  • Research Design and Methods

Background:

  • Traditional qualitative research often relies on the concept of
  • saturation
  • to determine sample size, a method that is inconsistently applied and methodology-specific.
  • This approach can be ambiguous and may not always ensure the adequacy of the sample for the study's objectives.

Purpose of the Study:

  • To propose a new framework,
  • information power
  • , to guide the determination of adequate sample sizes in qualitative studies.
  • To offer a more consistent and applicable approach than the concept of saturation.

Main Methods:

  • Development of the
  • information power
  • concept, which posits that sample size is inversely related to the informational relevance of participants.
  • Identification of key factors influencing information power: study aim, sample specificity, use of established theory, quality of dialogue, and analysis strategy.
  • Presentation of a model illustrating the relationship between these factors and information power.

Main Results:

  • The proposed
  • information power
  • model provides a structured approach to sample size determination in qualitative research.
  • Factors such as study aim, sample specificity, theoretical grounding, dialogue quality, and analysis strategy directly influence the required sample size.
  • A higher degree of information power allows for smaller sample sizes while maintaining study rigor.

Conclusions:

  • The concept of
  • information power
  • offers a more robust and adaptable method for determining qualitative sample sizes compared to saturation.
  • This framework aids researchers in planning and data collection by focusing on the informational yield of each participant.
  • Implementing the information power model can lead to more efficient and effective qualitative study designs.