Background: Sample size considerations in qualitative research typically rely on saturation, which broadly refers to the point where no further information is obtained from interviewing additional subjects. Achieving saturation of concepts or themes is often used as a criterion for discontinuing data collection. However, few studies report in detail on the process of achieving saturation.
Objectives: This methodological study aims to contribute to the operationalization of saturation and offer evidence-based recommendations regarding sample sizes for qualitative interviews using thematic analysis. The specific objective of this study is to demonstrate how to achieve saturation in a methodical manner through the development and modification of a codebook.
Methods: The original study for which data were collected examined communication practices within the peer review process of biomedical journals from the editors’ point of view. We sought a heterogeneous sample of editors through purposive maximum variation sampling and conducted 56 semi-structured interviews between September 2017 and February 2018. The development of the codebook was based on the thematic analysis of the interviews and consisted of two stages: 1) inductive coding of six interviews (Table 1) resulting in the establishment of a preliminary codebook; and 2) application of the codebook to the remaining 50 interviews, resulting in refinement of the codebook and establishment of the point of saturation. Coding was performed independently by two researchers, at both stages, with subsequent consensus reached through discussion.
Results: Stage 1 resulted in 57, 36, 43, 27, 29, and 34 codes for the first six interviews, respectively. The collation of codes resulted in an initial codebook containing 28 codes defined in detail, categorised under 5 themes. Stage 2 is currently ongoing. Results will be available for the Colloquium.
Conclusions: Will be available for the Colloquium.
Patient or healthcare consumer involvement: This work does not directly involve healthcare consumers but contributes to improvement of data collection and analysis in qualitative research, where healthcare consumers are central. It may help to optimize recruitment and interviewing of participants and promote meaningful utilization of the data they provide, thus maximizing benefits for healthcare consumers in general.